How to Build a Pitched Roof - Carpentry Training

hello I'm Roger physically from

skill-builder I'm here today with Robin

clever and Robin is going to give me a

master class in roof construction

hopefully you too but the idea is if I

could do it anyone could do it so Robins

gonna take us through the whole job so

just a quick intro to this job is a

typical domestic extension it's a

wraparound extension we've got a flat

area on the top which is going to have a

glass lantern so we've got some flat

roof joists to put in we've got a series

of rafters to go around it's a little

bit tricky in places but I'm gonna teach

Roger a few tips and tricks about how to

set this thing out easily I've got my

plan but if anyone is in the business

that I mean you get a plan one to fifty

it's only indicative of what they want

to end up with when you actually get on

site you see the walls in and the steel

working you've pretty much got to work

with what's there and make it work so

that's exactly what we're gonna do


okay so around the perimeter of the

building I've got a lean-to type roof

and I've got to make a lot of

assumptions here and I've also got a

calculate for different elements for

example there's a warm roof going on

here so the level of our steel work here

actually represents the top of the

actual structural Timbers then we've got

a fir in peace going on there then we've

got ply after that we've got 120 of PIR

which then as the membrane bonded

directly to it so what I need to do is I

need to bring my rafter up get it to the

right height to enable when that PIR is

in we can put the trim around a nice

hard edge like a Ridge straight over the

tiles so the first thing I need to do

although we specify what angle to have

these is just simply check these simple

thing section of timber straight on the

top and then we're just going to mark a

line my level is a bit long but it's

perfect I'm gonna line them up and we're

just gonna take a line here alright that

goes down to the bench with me I'm gonna

use my roofing square so check the pitch

and I'll set everything from that the

other thing I need to do is measure it

up now normally I use a simple

calculation which is basically the run

which is the level run by the degree of

pitch or actually the diagonal

measurement for that particular degree

of pitch so what I'm going to do here is

called stepping off so I've made a

little drawing for myself

and I've done all the dims on it so I've

used a level to check back the distance

from the front edge of this deal to the

outside edge of my plate I've done the

same from the top

to there and now I'm going to use my

roofing square on the stepping off

method which is simple because there's

measurements out either side and I'm

gonna step that off up my rafter and

that will give me exactly what I'm

looking for and I'm gonna go and do that

now and Roger is gonna drill some holes

for me let's work out the pitch take my

roofing square this was a level line so

effectively that is the rafter slope

that I'm working to it wants to be 35

degrees that's what we asked our steel

worker for

and basically that's what we need for a

plain tile so on my roofing square I

line this up with my common rafter run

pop it along there and I'll clearly got

35 degrees so I'm gonna set my roofing

square up I use this special modified

section of iroko which I made is like a

fence and although I'm not gonna go

exactly into how this roofing square

operates that it's basically like a

protractor and if you can imagine the

center of the projector being a fixed

point here in this case and in all of

these angles go around in a semicircle

that's effectively how it works so

that's the center of the protractor

that's 35 degrees best level and that's

plumb so that's a plumb cut and that's a

seat cut so what I've got is a little

dimension of the draw in here I'm using

a 150 rafter and the reason I'm using in

150 rafter it's only a short span is

purely to accommodate enough PIR

insulation maintaining an airspace over

the top and that gives me basically what

I'm looking for in terms of the build up

for insulation purposes

so we've a rafter we have a bird's mouth

that sits over the plate in tradition

that's always a third of the thickness

of the timber so in my case I'm using a

150 rafter so it's a hundred millimetres

from the top of the rafter back to the

corner of the bird's mouth I've also

worked out the level of the soffit in

relation to the heads of the window

frames and door frames simply by putting

a spirit level on the wall plate

measuring down and making an allowance

for the thickness of the soffit board so

in my case my drop is 275 millimeters

the overhang I'll cut that off

afterwards but I always cut my seat cut

first because it's really awkward to try

and get a saw in afterwards level that's

my seat cut right on the end of the

timber I've selected a fairly straight

piece for this because it's effectively

my template I'm gonna repeat these cuts

over and over again the next step is to

measure up

my drop which is 275 millimeters so when

I run the set a square here on this


I've got millimeters I've come to 200 I

can mark a simple line through go back

and I can add 75 millimeters on to that

which is 75 here that is the level of my


there we go now we know we want

two-thirds of the rafter in our case is

150 simple math makes it's a hundred mil

that's two-thirds there we go so then we

use the square we slide it down the top

edge of the timber and we mark the birds

mouth so there's your birds mouth that

effectively sits over your wall plate

all right I'm gonna mark the top of the

rafter now and the way I'm gonna do that

is by stepping off the height from my

wall plate to the top of my steel is 750

millimeters and I'm gonna step it off

again using it's very simple 200 mil

every time there's my 200 bang I'm gonna

mark that 200 I'm gonna go again 200

gonna mark that there we go again 200 so

we are now at 600 yes 2 4 6 I'm looking

for 715 add another 100 and hundred and

15 excuse my poor English that is the

level of my steel so I'm gonna write on

their level of Steel so why don't you

just get a tape measure of me because

Roger I'm measuring up an angle at 90

degrees so if you can imagine can't

measure this way because that's the roll

measurement I'm actually looking for the

measurement up that way 750 so this is

called stepping off to change things

yeah I also know that in my case I've

got a steel here like this I've got a

rafter which actually passes it and on

top of that steel I'm gonna sit a ridge

okay now that Ridge accommodates the

roof insulation which is 120 the plywood

which is roughly 20 and the end of the

furring which is about 10

so when you add all that together it

actually comes up to or I actually

worked it to the height of this timber

which is the same as the rafter so it's

effectively my Ridge so I need to do

then on my stepping off I know that's

the level of the top of the steel but

I'm actually going to add on a ridge so

I can use the ridge I'm going to use pop

a mark there now I know that's the very

top of my rafter

so my final seat cut here on the top is

here that is the top of my Ridge now the

next thing I know is I need to position

that Ridge and it's exactly the same

method stepping off however the distance

in to the steel is a thousand eleven

hundred and five millimeters that's from

the outside of the wall plate to the

outside of the steel I'm gonna step that

off again and it's gonna be somewhere

near it this time we step it off using

the different scale the the scale on the

other side when you say somewhere near

it I've never heard you use that froze

before well the reason I say somewhere

near it's because I've actually said the

steel work was set out for this roof so

I know it's gonna be roughly in the

field because I oversaw the setting out

to steel work I did the steel drawings I

signed the steel drawings off on this

job purely because I know I needed to

pitch a roof on it afterwards so this

time I'm going to just use the 300 scale

and there's 300

there's 600 there's 900 now we need to

add the odd beyond which is 215 there

that is effectively my ridge board so

what that what that means is then the

corner of the steel Varitek will talk

about the level of the top of the steel

and that's the front that's exactly

where my steel is so on the roof that's

the where the steel is and you can see

it's perfectly positioned for me to land

a nice piece of Ridge on top of the

steel and that's my rafter coat gotcha

gotcha yeah yeah and then what we're

gonna do use a ridge it is a ridge it's

a ridge gold yeah thinking it was a pike

when I was yeah it's actually a ridge

board which we're gonna then bottom fix

through the top flange of the steel

you're gonna drill the holes for that

and then we're gonna bolt that up there

but we'll build all the roof on first

because the Steel's are never that

parallel they're always a few mil out

and this way it also eliminates I know

the steel as a level and the plates are

level and this way this will land on the

steel and it will just run in and out

and then we'll bolt it up afterwards

we'll attach all the roof together one

of the things I think the real skill in

this for me the experience these

experience because you've got a little

bit of discrepancy in the timber yeah a

little bit okay so you turn it always

those rounds that are all the same way

round but I noticed when you put that

square on yeah yeah there was a bit life

between between there yep and there yeah

and you're telling me that even the

stills on completely uniform as it yeah

so all those millimetre this is what

gets me as all those millimeters yeah up

yeah you know and by the time you

finished it we lost three days Osbourne

and then suddenly I'm looking at a gap

that you could drive them like though

you know so yeah that's where you you

kind of really score because you've done

it before

yeah so you gotta build a bit of

tolerance in and sometimes if your chip

if you're a chippy and you've done ruse

before sometimes you know you get there

the place have been bedded on nice and

level but they're not true and they're

not straight so sometimes you do have to

do knock the plates backwards and

forwards and secure them maybe we have a


but which you can just burn nice drill

through and screw them down or even if

it's a soft block you can actually shoot

your nails into them although it's not

advised by the nail gun manufacturers

that you shoot into any kind of masonry

but you can prove into a soft block and

that was just secure them and hold it I

do it all day long dear yeah and

everyone else does too so moody

intensity blocks so take a fixing like

that so I'm gonna cut this up and I'm

gonna make a template now the front

steel and the side steel were different

by 100 mils so the rear steel was too

far back so when I do the rear section

of rafters got added another 100 mil on

onto my plumb cut what that looks like

sorry Roger is simply measuring another

hundred mil so the rafter on the front

is going to be exactly the same except

the position of the ridge is going to be

here so that's my that's my side steel

and that's my front steel that's gonna

be the ridge there yeah so that pitch

robin yap way round is it the same same

pitch 35 degrees all the way around yet

think about that yeah it's the same

pitch you're telling me it's longer all

it is easy okay so same rights and

plates the same eye tops are same might

yet place the same height tapas and the

pitches the same height pitch is the

sames two bit longer it's just the fact

that if you can imagine if that's my

steel and that's my plate the one on the

back is just a bit further in I think

they just could have calculated that a

little bit better on the sitting out the

steel people but at least it's not the

wrong way at least it's not too far


yeah and it's fine I can still work it

and that's all good so that's it the

next job cut these rafters up get it all

ready and then we'll start putting the

thing together all right Roger better

get on one yeah you make on with the

drilling the drills down there the bits

in it


but is effectively a rafter this is sort

of indicating the wallplate this is an

oversized rafter structurally for what

we're doing look at the span and it's

nothing the reason we're doing this is

because you're going to have PIR here

100 millimeters of insulation there yes

an airflow in fact it's underneath and

air flow over the top yeah so on the

warm side got the insulation and then

you've got air flow over the top

breathable membrane or a vented fascia

board don't go there to counter bet all

day long you could do all right I love


I've got colored rafters you're drilling

my holes let's get on with it


so there's a series of marks on this

plate which represent rafters window

openings instead of trying to sort of

measure everything up and we measure it

up I measure it once mark it out really

accurately cut myself this rod mark it

up when I put my region I just transfer

the rod up square everything down is

eliminates all of those sort of like

measurement mistakes because it's really

easy to gain a few millimeters here in



myself it's not good isn't it


I'm just using my rod I'm making my life

easy yeah well this is just this is a

fail-safe and will do any ministry and

once I've done it once so the next job

is I'm gonna square this up so I've got

my n2 rafters even got my Ridge onto my

plate as well I'm gonna take a diagonal

measurement between the two and I'm

gonna tap them backwards and forwards

until they're perfect the reason I'm

doing that is because we've got some

roof lights going in here they're quite

small apertures there's one there's 600

500 it's a standard sized roof window

but by doing that when I actually trim

them out and frame them up I know

they're gonna fit square as well so it's

pretty important that you start square

and excuse that finished square to

so now that is the difference of 15 mil

so I've measured my two long diag and

also I'm gonna make them exactly the

same now then I know that I'm exactly

ninety degree for my wall and my roof

lamp is a fitter crease yes Roger don't

forget as your apprentice yes was used

to be an element of learning in this not

just cheap labor not just drilled a hole

so I mean I've drilled holes before

quite honestly I've got a site in my


drill quite a few holes yeah well then

get on and do it stop something about it

what I'm gonna move on to pastures new

well in a minute I might even let you

now so now see and Roger how about that

what if with your West Wing we've most

been caught look at that the sun's

really strong today it's lovely tell you

what Mike while you're there yep done

with video oh man that was lovely

that was lovely that was that was suited

up yeah I actually gotta say I enjoyed

my drilling today good we took your time

over it so we must've loved it

like you're the man you know man when it

comes to coffee you know man when it

comes to Brookline well she got hidden

up your sleeve onto their onto their

parallel no no oh you want me to go in

it yeah come on Roger

coffee coffee you tell your son I can't

yeah it's all gangly so I'm happy with

that position there Roger so I'm gonna

put a mark somewhere and then we're

gonna bolt that Ridge in but before we

pop that Ridge meeting we're gonna

straighten it up by putting the rafter

in the middle and then it'll be nice and

true then it's got the plate nice and

true so that's what we're gonna do next

there's a little bit of a bow in that a

little bit in the ridge

yeah yep so it's fixed at either end and

obviously the timbers are always a bit

wainy but as soon as you put in a few

more of the rafters providing your place

nice and straight which it is in this

case we just check it out we'll just

give it a little tap we have a pink

flush look at there and there you go you

should have a nice straight rich now and

then we'll fire that in here we go nice

and true there we go

what's that mate dive-bombing tape I'll

go get it

I'd like to volunteer to be the one who

goes down and gets the tape mr. mennick

go on in

this piece of timber not only was it

that way just at the end there needs to

be forward through the slides up yes

there needs to be so the bolt brings it

down there yeah we all know should we

bolt it first before we fix well we need

to probably get another hole under here

to catch the end to get that to get that

pulled down okay I'll do that

maybe you can do that first yeah yeah

through that through and then we'll put

a bolt through it that's nice



did you say am i happy

yeah if you say that I did

I love these be happy but that's a deep

question yeah this is a this is a rule

no no doing this so some of this or that

that's what moves doesn't it back in the

day when people used to smoke this

believe it or not was the measure of all

things they used to say you call a

pipe that between that so let's just

have a little look give it the Rizla



I think he's alive he's alive the boy

done good I say this is often a problem

where you have a steel and a plate and a

rafter that hits it so what I like to do

is just mark it drill a hole couple of

cuts instead of taking another bird's

mouth out of it just think it looks a

bit special then when you're working

with tantalized timber

so structural I always use a galvanized

now three-point one by ninety ninety

millimeters being the length three point

one being the thickness and their output

for roof construction you don't want

anything shorter than that it's got to

be strong


got a few lumps and bumps into me going

after that we're a service now you're

quite sure are much cheaper yeah this is

fine absolutely fine



so it's my schoolboy error because

funnily enough I'm human so put my

window trimmer in the wrong place I've

got to take it out and anyone who knows

how well these nails hold so I've got to

get the thing out and read and redo it

it won't take me long I actually need to

cut nails out in situ so I'm gonna try

and give it little knot and make a

little bit of a gap in the top you can

see how solid it is there we go that's

giving us a bit of airspace now we need

to cut that now that first of all in the

top let's run this sword blade down


that's the first one done got another

couple to do your art Robin yeah a bit

from here

well let me try and get it up there


that's lovely perfect so that's released

the house is the goose giving a sort hey

you go come from around the back yes

what they all say


I'm gonna shift this over there we go

misty now that very often it's very rare

all you get to use my hammer anymore is

now I'm gonna put that back in the quick

way yeah that's the way it is in life

yes so I've just got the window trimmer

there to set the whip for that that's

the crucial whip I use the same up there

small boy arrow boys


what's next I need you to make some

bridging or some logins okay they need

to be 353 every single one that said

that means when I put that in between

two joists yeah you've got a Caesar for

fibre measures bang on for 400 or was it

yeah so you've got a template or you can

set something up you can clamp a bit of

timber to there yeah but not knowledge

yes I've done a bar can you make me to

start with I'd say 12 because there's a

few that we need to make a different

sizes okay so dozen or a dozen of those

got the end stopped there so that it

can't go back too far that's it he wants

12 of those

never used this saw before but I tell

what I really like is if you have to

hold the timber on that side and you

want to use it left-handed you don't

have to worry about pressing in because

this bit of your hand can go in there so

normally you use it with your thumb on

the safety there so if you want to be

holding the bit of timber and you want

to use it

left-handed what you can do there is you

can still operate that safety

on there which is really good because a

lot of the time if the way they've

designed that switches were allowed you

to heal it in so full bar for that so

I've got some small roof lights going in

this slope so I space the initial

rafters out to the width of the aperture

that is gonna have another one on either

side to form a double I mean really it's

plenty strong enough to do the job

without doubles on these but I like them

sketch the battens all the way up the

side as well so they're outside of the

flashings etc so what I've got is

parallel trimmers which slot in between

I've got a top one and in this case a

bottom one which is beveled off because

it actually sits over the plate all

right over there now to put these in

I've got my my foot already cut and I've

got my top already cut so what I did I

took my rafter I marked the window on it

and then I cut the top in the bottom off

now that's what I'm gonna use to put

them in so it's simple I offer the top

in mark the shoulder same with the

bottom put the bottom in mark the

shoulder so they don't know but I do you

can take my and I've repeated that

process on the other side take my

trimmer when I fix I'm gonna fix that

home and it's basically all worked out

for me so when you get that fix home

there let's turn the gun on its turn

itself off which is always good

that's good saves the battery if you

turn it off the other side in then we're

gonna put the foot in now the foot is

simply in the middle there you can see

how nicely it fits because there's no if

you try and measure all this stuff

there's too many bits to go wrong we'll

put that we'll put that foot right in

the middle there there we go

so we'll get a fixing round into the

plate down into the top and then to get

the top in exactly the same deal come

out the shoulders get your trimmer

incidentally I've cut all the trimmers

exactly the same my shoulder marks there


it's got a nice feature on this

particular gun check this I like this

feature especially for doing decking you

know putting a roof deck down how about

that so quick there we have it


no no inside that's the aperture yeah

all right hold it there for a minute all


now Roger you're gonna pass me we'll

just leave that just to one side come

over here I'll put it on for there keep

yours coming on your roof there

that's it might leave that to there for

now we're gonna get buried real and a

couple of those bolts off the back you

know the short 460 from the inside

that's it right the same again there


she's gonna cut those quickly all right

be back in a second


yeah safe and they tend not to split the

timber because all nice and they're not

countless something too so anyway so

that we just drop this in now perfectly

even between there and there and we've

we get all that attached up to itself

we'll bolt that together so you feel a

lot of timber has cut copping in it

she's like that so obviously I've got

more Timbers coming this way so I'm

gonna run my cup towards those Timbers

so it's a bit more and bit more straight

on the inside I'll back it up with a cup

as well so it's nice and tight but I

won't run the inside one round until

I've got these ones in and fixed before

I do the hanging so I'm just gonna

attach these up here and then we're

gonna spray it all up what you have

small box out that little box down there

may place the cardboard box behind my

favorite team in the world square it's

probably my roofing square really

because it's simple but it's been with

me ever since I left college and before

that same one really no but I consider

that to be kind of like my voice all my

qualifications all rolled into one

really and it's where I kind of it was

the thing I enjoy best is making Rouge

complex timber structures but you can

use it for a whole lot of things as well

but equally a small carve to square a

square these are really good as well you

know actually I'll tell you what if we

did a video one day on yeah as

complicated bit of kit yeah I mean yeah

well it's the same principle except them

the protractor is from the pivot point

there there's your degrees of protractor

like that yeah my one it's got little

notches in it yeah which is good for

doing parallel scroll area but there's

all sorts of little things is about half

a dozen clever little things

one bite and this is the best way you

know what this one's for this one I did

no actually that's for hanging on the

shelf in the shop oh that's lovely

no it is it's know what comes next

squaring it out battle across the top

and then we can do it everything off it

in this that's pretty straight but

beautiful right Dave I need your help

here you're gonna hold the tape measure

your one into there I'm gonna go measure

it over to there in fact what I do is

I'll go back on to the other Tower and

we'll do it from there and then we'll

get a brace across the top which is

Rogers gonna get me a piece of button

okay so what I want you to do though is

we need to increase this length and

decrease that length so how we do that

is we just knocks if you go to the ends

you're just gonna tap the joist over yes

you're gonna go that way say five mil in

the steel I said let's try that again

because this is to be exactly the same

measurement and we cannot go wrong then

so this is the opening for the this is

the lantern answer I mean yeah I'm just

gonna straighten it up check it for

straight to come unstuck here not me may

have worked it out good I'll spend my

life working things out good I need some

6 4 to 3 bits yeah I know kids are what

they just need to be like 300 long

they're just a space to steal off we

know work that one backfiring spread

these out knock them out and then go

boom what's it that's busy that's my

window trimmer


300 throb please Roger that when you say

take 3 out of it I thought I'm gonna

have enough timber now helps me to know

when I said cut free at 300 I've even

been cut free any size you want now

we've created this large aperture it's 2

meters by one and a half meters it's

gonna take a roof Lantern and so what

you're taught to do is parallel

everything up all on the measure and

then we used an equal measurement across

the diagonals to get it exactly square

and so then I always like to pick up a

sight square as well and use that just

to double-check we're all in good form

oh it's absolutely spot-on that's it

he's bought on these if the lanthum

doesn't fit they've made it wrong thanks

Dave good buy this rattle these last

joist in space them all out everywhere

trim everything up they need to be just

spaced up enough and they just so they

don't rot that's it why is it today

Robin it's Valentine's Day what are you

doing tonight Robin atheist whatever I'm

told would yeah if it's a real question

you are actually going home tonight yeah

I'm doing whatever I'm told because I

figured in life that's always a good

good mood

I'm here in my flange I'm here in my

bracket day I've got something in the

way here which is gonna be tricky isn't

it be sure to cut that bit shorter no

it's not no it's not you easy to find

job Roger this the other clowns and it's

the one we squeezed in last isn't it so

alright we'll come back to that one


Roger can give me some more now well you

know yeah guess the three or four reams

please my best is under the baton Dave

and the Timbers on the button here so

it's a bit tight that's right

any selling today oh yeah oh yeah and

then you can have that on there yes


why don't I have a slightly shortened

knotch now I would say do it in the way

yeah okay tell me when to you to me to

him to her stay there for me well I

reassure myself

you're gonna go tight your end I'll go

under my baton over here and see joists

yeah I words you all out

take your side first Dave on that that's

it mate all right

somewhere there ready put that one over

there just over there for a minute get

the last one in all right they go might

give us a couple of nails in there okay

Robert I think it's time to go it's

getting dark enough and the cameraman is

getting grumpy how about that I always

been busy all day watching you work what

can you do

timber work I haven't found it a lot

yeah it's been good at yeah yeah I think

if I had a choice between being a carpet

or a cameraman I'd be a cameraman would

you yeah okay that's fair enough it's a

bit disappointing out in one day with me

anyone's to leave anyway it's big good

yeah thanks man dirt you're gonna come

back again and do a few more waves for

us and we are wrong yeah we've got some

interesting rules coming up this year so

as a when we'll pull you up and get you

down in here and if you're not a

subscriber become a subscriber because

that way you can keep up to date with

everything that province doing have a

look at his own channel as well because

that's coming on nice evening yeah just

do sort of bits of filling bits between

what is it Roger keep saying that it's

all good stuff is it yeah it must be

good if you think so so thanks mate I

come on cheers Cheers