It is currently 28 Mar 2024, 13:00
Richard39 wrote:.......I had an idea for a slight change to the third course of bricks, and that is to replace it with a course of plinth stretcher bricks. This would remove the need to install wedges under the bottom board as it would sit naturally in the recess created by the plinth stretcher brick, and any rain would just wash straight down the bricks. Can anyone think of a reason to not do this way?
Andyp wrote:Hi Richard and welcome to the forum. As you have seen there are plenty of very knowledgeable folk around here who I am sure will be along in a while to answer your query.
It might be better if I move this post into it's own thread that way you can add some photos as your build progresses. You will need to create a couple of more posts for the spam trap goes away.
9fingers wrote:With the heights you mention, you could fit joists at wall plate level and these would be 2.3m above the floor. Identical to most housing. these would be in tension from a roof formed of a pair of rafters per joist and only needs a modest ridge board. Depending on roof cladding and rafter length, these could be at 400 or 600 centres.
This style of roof puts minimal load onto gable walls and so the lintel over the garage door becomes little more than a catnic - subject to calculations!
With one or two of your adjacent rafters doubled up and a pair of acrows temporarily added would support a block to take out an engine etc if needed.
Dan0741 wrote:Richard Welcome to the forum, you join the ranks of a fair number of self builders! Your project sounds interesting, I know you said its just a slab, but photos inform and seem to make the wheels turn here, see if you can get some posted as soon as you are able.
All the best
Dan
9fingers wrote:.....From the point of view of the roof alone, the rafters are in tension and so don't need to be very high. The rafter bear onto the wall plate. The problem comes from the storage requirement which put an imposed load on the the rafters. Could you contemplate any support pillars under your storage area? It would possibly give you another 100mm headroom all over.
Bob
9fingers wrote:I reckon with a bit of cunning you could get the eaves height to be a small fraction of the joist height added to your wall plate level by knocking off the top corner of the joist and the thinnest of fibre cement slates.
From the point of view of the roof alone, the rafters are in tension and so don't need to be very high. The rafter bear onto the wall plate. The problem comes from the storage requirement which put an imposed load on the the rafters. Could you contemplate any support pillars under your storage area? It would possibly give you another 100mm headroom all over.
Bob
Mike G wrote:9fingers wrote:.....From the point of view of the roof alone, the rafters are in tension and so don't need to be very high. The rafter bear onto the wall plate. The problem comes from the storage requirement which put an imposed load on the the rafters. Could you contemplate any support pillars under your storage area? It would possibly give you another 100mm headroom all over.
Bob
Could you just explain this a bit Bob, please? Rafters are in compression in a simple truss, with the tie (bottom chord/ joist) being in tension. I can't see how anything stored on the joists imposes a load on the rafters.
If the joists are struggling with storage loads, then hangers are the traditional solution: a tensile member hanging down from the ridge board at every (say) 3rd rafter, bolted to a rafter and the joists, with a binder alongside on the top of the joists to ensure that they all act together rather than deflecting individually.
Dan0741 wrote:I am so envious. My slab is about 30m from the nearest place I can get with a vehicle, every block, brick, slate and all the wood has been carried piece by piece up the garden.. That will save you a considerable amount of time!
Mike G wrote:Hi Richard, and welcome.
Your joists need to be 220 x 45/50 at 400 centres for that span, if they are to take a load (storage above). I suggest leaving an access door in the gable so that you can feed long lengths of stuff in. You shouldn't really be notching out of the joist to get the roofline lower, but if you must, 50mm at most, and I would nail a bit of something along the wall underneath just to be on the safe side. As I said above, if you are planning on storing lots of weight up there, then consider hangers and a binder.
OK, on re-reading I see I have misunderstood. You are talking about taking the top corner of the joists off to fit them below the top line of the rafters. Well, with a birdsmouth and rafter feet overhanging, there will be a minimum thickness left in your rafter, so it won't be as per Bob's drawing. There is no problem cutting a good chunk off the top corner of the joist. It's standard practise.
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