Fitting new cony/workshop roof ?

[W.olly]

Hi all

This a long time needed job to be done, which is to reroof the workshop which was a conservatory so has UPVC windows all around but for the rear 3 foot of the side walls which is brick wall. so two 6` windows either side and two 6` windows at the front with a central door. And is a flat roof.

I was going to fit a GRP roof but this way is quicker and better price wise. Which is to use 50mm thick Insulated roofing sheets.

The area to be covered is 15 foot wide and 10 foot deep. so not massive. I can get sheets in the full length needed which is good so my only question is.

What size purlins should i use, if i can find them long enough for the 5m width ?

Or will a rafters be ok due the the 3m depth of roof being so short ?.

Thanks

 

[gaz1]

what roof type are you fitting ?

as cant answer until you do

 

[Keith 66]

If its a flat roof check the minimum pitch required, Im replacing my workshop roof in next few weeks, insulated steel roofing sheets & min pitch for those is 15 degrees. Its currently got a ropy old asbestos roof, the original purlins are 2x3 but are riddled with woodworm.
Because the roofing sheets are a fair bit heavier approx 29kgs per 3m x 1m sheet i have gone up to 4x2 partly because that was all the builders merchant had in pressure treated! Big shortage of 3x2 apparently & a lot of other materials are in short supply.
Roof sheets will be here in a couple of weeks.
Praying for a week of good weather. "When de sun shines de roof dont leak, when it rains i cant fix it no how!"
Going to buy a big tarp next week just in case.

 

[gaz1]

5 degrees with a metal roof but ends must be filled to stop water entering underneath from front and rear

and also allow it to breath as well

 

[W.olly]

what roof type are you fitting ?

as cant answer until you do

In the post kida the insulated roofing sheets. All i know is the steel type with PIR sandwich type. What others are there, could be another way then to go

If its a flat roof check the minimum pitch required, Im replacing my workshop roof in next few weeks, insulated steel roofing sheets & min pitch for those is 15 degrees. Its currently got a ropy old asbestos roof, the original purlins are 2x3 but are riddled with woodworm.
Because the roofing sheets are a fair bit heavier approx 29kgs per 3m x 1m sheet i have gone up to 4x2 partly because that was all the builders merchant had in pressure treated! Big shortage of 3x2 apparently & a lot of other materials are in short supply.
Roof sheets will be here in a couple of weeks.
Praying for a week of good weather. "When de sun shines de roof dont leak, when it rains i cant fix it no how!"
Going to buy a big tarp next week just in case.

I was thinking 4z2 myself but as which timbers, spars or purlin ?

 

[Keith 66]

Mines a large double garage ends are a wooden truss with two wide steel trusses spaced along the length, purlins sit on those.
Its complicated by the fact that the whole building slab it stands on slopes down at one end by nearly 3" & i have to level the roof up to cure drainage problems, at moment the fall is towards next doors garden not the road & i cant get gutter water to go uphill!
Once its leveled up the gutters will go into the new drain on the driveway & away.

 

[frank horton]

wolly,
either of those distances....ie 15' or 10' ....steel insulated roof pannels would be self supporting.....
every sheet I have fitted has a posative lock when joining the sheets....
not so nice to get locked in over 7.5m. I did struggle last time but there was only 2 of us........
obviously u will need to walk over it so some kinda support will be nec.....
for me I'd buid a temp support just for const
ruction.....
BUT...
this depends on secure attachment at the ends....the wall plate will not be a prob.....
its just a secure means of attachment at the other end......
some UVPC if not all conserv frame work should have a steel core......
so that would ease the prob.......
lastley is this in a shelterd position wind wise......
this sounds a quick aftenoons work once ur organised....

 

[W.olly]

wolly,
either of those distances....ie 15' or 10' ....steel insulated roof pannels would be self supporting.....
every sheet I have fitted has a posative lock when joining the sheets....
not so nice to get locked in over 7.5m. I did struggle last time but there was only 2 of us........
obviously u will need to walk over it so some kinda support will be nec.....
for me I'd buid a temp support just for const
ruction.....
BUT...
this depends on secure attachment at the ends....the wall plate will not be a prob.....
its just a secure means of attachment at the other end......
some UVPC if not all conserv frame work should have a steel core......
so that would ease the prob.......
lastley is this in a shelterd position wind wise......
this sounds a quick aftenoons work once ur organised....

Thats sounds good kida, i remember many many years ago when i was in demolition removing these sheets and they were dam strong. So i did wonder if any was needed on a small span of 3m. But wasnt sure on the 50mm thickness being unsupported as i used to rip out the 100mm plus sheets.
The cony is fairly sheltered no direct wind.

Thats another reason i would rather this system than GRP roof, a lot quicker.

 

[gaz1]

the rafters for the roof can be 1m apart except for the ends which need to be close but not too close to the end to fasten the ends down about 200mm in from the end for the screw fasteners

@Keith 66 id use wood for a speed reference to make your end higher not a flat roof but slope it the other way towards your own property doing it by block work you wont have time to do it

size of a full block would be enough to give you a slope

i had to do it fast for mine

 

[Keith 66]

My workshop is a double garage with standard pitched roof, the long axis (central ridge) slopes downhill towards next doors garden, a right pain. We had a new driveway last year with new drains, now i gots to raise the roof slightly at the far end so the gutters go into the new drains rather than pouring into next doors garden! The whole garage slab is 2" lower at that end, Its a concrete sectional jobby so i have to work with whats there.