Building timber roof

[zemphis]

I am hoping to build a roof between two walls to create a shed/veranda for storage space. There is nothing there at the moment. The size of the shed will be approximately 8 foot wide by 12 foot long. I have been thinking about using two big 2"x6"x3m timbers for the sides and bolting them to the side walls about 6 foot high. Before doing this i will need to cut out notches on both timbers for the top rafters to sit on. Can anyone look at my plan and please offer any advice or confirmation about whether i am going about this the best way? I have attached a sketch too:

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• zemphis
• 30 Jul 2010
• 1

I would use 2"x4" or perhaps 2"x6" timber for the main rafter support between the walls. Then all of this will be covered in 12mm plywood along with some roof felt to make it water tight.
thanks

 

[ColJack]

6 foot is a little low
why notch them? what's wrong with using joist hangers? it's good enough for a floor...

don't forget you'll need a pitch to shed the water..

and I'd use 2x6 for the rafters, at 8 foot wide that's a lot of weight when it snows..

 

[zemphis]

6 foot is a little low
why notch them? what's wrong with using joist hangers? it's good enough for a floor...

don't forget you'll need a pitch to shed the water..

and I'd use 2x6 for the rafters, at 8 foot wide that's a lot of weight when it snows..

Thanks for that useful info. Youre right i will go with 2x6 for the rafters. Rechecked the ground to roof height and it will be just over 7 feet. The pitch has been worked out aswell. Also the joist hangers are spot on and will save extra chiselling work.

Any advice on what size anchor bolts would be best for securing 2x6 to the side walls? Ive been on the screwfix site and still not sure which ones. These are the ones i have looked at:

anchor bolt1
anchor bolt2
anchor bolt3
anchor bolt4



thanks

 

[DSA]

You need to establish what load will be applied to the fixing in order to select the appropriate one and their centres.

I imagine that it may be worth considering snow drift if this is between two walls which are higher than the roof level of this canopy.

What centres are your roof joists at? 12mm plywood may be on the thin side, particularly when considering deflections. I would also give due consideration to making sure that the walls can take this additional loading.

 

[zemphis]

You need to establish what load will be applied to the fixing in order to select the appropriate one and their centres.

I imagine that it may be worth considering snow drift if this is between two walls which are higher than the roof level of this canopy.

What centres are your roof joists at? 12mm plywood may be on the thin side, particularly when considering deflections. I would also give due consideration to making sure that the walls can take this additional loading.

Yes youre right because there is the higher house roof on one side. So with heavy snow there is the possibility of it drifting and landing on this new roof. The other side wall is lower.

There is one main consideration i need to add. There is a roof gutter running along the full side of the main building. So at some point it will be necessary for someone to get up on top of this new roof with a double ladder against the wall to occasionally clear that top gutter.

The side walls are about 9 inches deep. I agree with you about the ply aswell and i was considering upgrading the spec. So it will be 18mm deep now. The joist centres i am thinking about 450mm, which will give me an even spread of about 8 rafters.

Does this sound ok? thanks

 

[zemphis]

If anyone can help with this aswell. I bought some 2x6 and a joist hanger. But the hanger is longer on the back and has two sharp corners sticking out. So i am assuming these are designed to go into brickwork. But since i will be fixing them to the side rafters will i need to cut the ends off or should i just bend them down behind the rafter with a hammer?

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• zemphis
• 3 Aug 2010
• 1

Also i am still undecided about the wall bolts. I have bought a couple of M8 and M10 bolts. But i have niggles about both and they maybe the wrong ones. Is the M8 diameter enough? And the M10 bolt is not the projecting anchor type. Because i need to fix the bolt into the wall first, then be able to slide on the side rafter and then put on the nut. Would 10mm diameter bolts be enough? With 5 on each side rafter securing it to the wall.

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• zemphis
• 3 Aug 2010
• 1

thanks

 

[Deluks]

These

...would've been adequate, fixed with round headed (not countersunk) screws. So you're best returning them if poss. otherwise cut them off with a hacksaw/jigsaw as they'll get in the way if they hang down the back.
12mm ply will be ok for a simple structure as this. But down our way 18mm is cheaper because they sell more of it. OSB will be ok as well.


bigger is better for bolts, you get more friction with a bigger bolt. Best to temporarily fix the beam with screws/plugs, then drill a hole through the timber, then swap over the bit for a masonry one and carry on through. otherwise you're messing about lining holes up.
The second bolt should be ok as long as the protruding bit is roughly the depth of your timber, and you drill the hole slightly deeper than the expanding section.

 

[zemphis]

Very good advice Deluks thanks,

Ive returned the other hanger and gone for a different one. It was actually on the same page as the link you provided truss hanger. They are more expensive but larger too. So i hope ive chosen the right one for my 6x2. Also i will have to fix these hangers to the timber using large head clout nails. Otherwise it means buying loads of nuts and bolts and drilling through the timber first etc.

Its the same here regarding plywood. I think 18mm actually works out cheaper than 12mm. So i will probably go for the 18mm ply once all the trusses are fixed in place and tested.

For bolts ive decided on some M12s now. I agree it will be much simpler using the method you described. Im planning to do it in a similar way. I hope i can manage it

Will return soon with an update.