Pent Roof Layout

by Simon


I'm between metric imperial so hopefully you will excuse a free-style for measurements!

I am designing from scratch, and for the first time, a basic pent roof shed. It's approx. 8' x 12' on the roof with about a 7.5 degree fall from front to back which works out about 300mm difference - I reckon.

From the base up - About 50mm hardcore with concrete flags on top, bearers then a 4"x2" joist at 400mm centres with 18mm OSB on top. The wall studs I'm planning in 3"x2" at 400mm centres again with the same for sole plate and double top plate. Rafters 6"x2" at 400mm centres with 18mm OSB again then felt. I've got a bit of detail with overhangs all round, fascia boards etc.

I need to have quite a wide door opening to get a mower in and out - with studs at 400mm spacing this is posing the question (finally!) -

- Must each rafter lie directly above a stud? I plan to double frame round the door opening and add a lintel arrangement. Do I need to increase my top plate to spread the roof load between studs?

Appreciate any help.


Hi Simon,
Thanks for your question. No problem with the mixing of dimensions. It sounds as though we are of a similar generation brought up on the cusp of decimalisation?

I have attached a sketch at the top that I think answers your question. The size and spacings of timbers sound good to me. With a single header plate it is best to have a stud under each rafter. To support the lintel over the door you introduce a trimmer stud that is bolted to the side of a stud supporting a rafter.

This is fine if you want an opening which is on the module of 400mm (16"centres!). If you want something different then you have the lintel spanning between the studs but pack the trimmer lintel off the stud to get the 'rough opening' size that you need the door opening to suit your mower.

I hope this helps. Let me know if you have any further questions. And of course send me pictures when you have finished the project.

All the best.


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