Shed Roof

5 Jun 2009
Reaction score
United Kingdom
Hi all,

I will upload a picture for this one later but when i moved in I had a 6x8 shed in the corner of the garden, I have since done the whgole garden over with patio, nice chips, etc, and i put a nice big extension on the side of my hut, so my hut is now 10 ft wider,

I started by knocking a wall and half the roof off my hut and building the 3 sides on it and then building up and adding the other half of the roof from there. I used chipboard for the roof and the floor. Also decent felt on the roof, all seemed fine.

It all went wrong when I painted the whole inside white, this sounds mad but the original was already white, so all I was really doing was matching new to old as best I could, but the big length of new roof now sags a big and isnt looking too good.

Anyone got any advice on what I did wrong, that was about 15 months ago, what I am now thinking is take the roof off and do it again but better with decent straps going from one side to the other, use the overlap felt you can get, ( I saw tommy walsh using it for his workshop project) and actually bring the roof out 150cm so there is a canopy to the front.

What upset me is Im an avid DIY'er and usually like to get things right.

Any advice anyone, sorry for the long speel. Ill add photos in a bit.
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first mistake "chipboard" wrong material for damp or wet conditions
12mm exterior ply or sterling board[fully coverd]for roof or floor assuming enough support

comments on the rest will await photos ;)
sterling board, thats what it was, sorry i forgot the name.

I know what I did wrong, its too far stretched and its too thin, must be 12mm or something., going 8ft accross and its also in sections. and is dipping in a few places. Stuff it im off to take a few photos to show you.
ok need to picture this lol
you have a shed 6ft wide by 18ft with an apex or flat roof!!!
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no it was 6x8 with apex roof, now 16x8 with apex roof but one bit of the apex is sound as it has never moved, it goes accross the 3ft, but the other bit goes accross the other other 13ft, thats the problem, it should have been strips I reckon, not boards.

Still trying with the pictures.
ok this ones a bit complicated :D

normaly you would introduce "A" frames to support the roof but in your case its complicated

i personaly would introduce a bit off 4x2" into the apex[top point] affixed to the origional ends and parralel to this 3x2" every 18 to 24" to support the new roof along its length i am assuming here the span[un supported length] is 7ft6" ish!! you need to allow for snow loading

you may need to affix a bit off 3x 2" to the top off the wall to affix the 3x2" to
far stretched and its too thin, must be 12mm or something., going 8ft accross and its also in sections. and is dipping in a few places.

Have 3x2 supports, not 2x2 when you do it properly. You will have to cope with snow loading in the winter. These could be fitted without removing the roof. and you'll need a collar to stiffen the rafters.
that isnt a bad idea, your obviously very knowledgable in the subject, ..

Being honest I dont quite understand what you mean, the more I read it the more different ideas what it means i come up with. I thought I would have to do a new roof cos id made a mess of it, regretably. Bujt you are telling me to repair this one ?
your roof is sagging through lack off support if the sheets are undammaged through wet you can temporaily prop the roof under the sag 1" above the finnished level by a bit off wood off the floor
idealy your supports on the side walls would match up closley to the roof supports at every 18 to 24" dependant on where the centres or joints are going to be
snap a concensus oilman :D ;)

I must have been writing as you posted, 'cos yours wasn't there when I started :LOL:

scott, if you prop off the floor, put a longish scaffold board, or similar, on the floor to spread the load, or you might damage the floor.
These are relly good suggestions and I tihnk I will braqce it with another length of 2x2 to prop it up.

At some point int eh near future though I am considering swapping the roof out for a better oine. Decent thickness planks first ( poss 30mm) with sterling board over it, then these overlapping felt tiles I saw tommy walsh using. I want the new roof to overlap about 1 to 1.5metres to the front for those rainy days.

Any ideas >???

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