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Loft Conversion

Upgrading existing rafters without removing roof tiles

Anonymous user 16/03/2024 - 2.38 PM

Hi, Currently in the process of converting the loft in to a proper storage space but not actually make it in to a habitable room. I have structural calculations from an engineer for the new steel beams, dwarf wall, new joists, new rafters etc. Existing roof is of TDA truss type, the existing rafters are approx. 3x2's and the engineer has specified these be upgraded to 6x2's by bolting to existing. My question is can this be done without removing the existing roof tiles i.e. from within the existing loft space? Looking at the way the rafters are shown on the calcs i believe once the new rafters have been slid into the eaves space above the existing wall plate i can't see how the other end will be able to pass the ridge board. Obviously if whole roof tiles need to be removed then this will increase costs which i could do without! Apologies, further details added to clarify. A seat cut (not a full birds mouth) is made to the new rafter at the wall plate end and at the opposite end the rafter is cut at an angle (approx. 30degrees) so it would butt up perfectly with ridge board when in place, however when trying to slide in new rafters alongside existing ones with the existing roof in place, the rafter actually clashes with the ridge board. It can't be moved further towards the eaves to clear the ridge board as it is already tight up against the wall plate and underside of existing roof. Hope this makes sense!

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4 Answers

B Batten Carpentry

Rating: 5 out of 5

New Malden

Hi. Your rafters shouldn't be passing the ridge board and should have a specific cut on them and then nailed, screwed to the ridge board. Hope this helps

Answered28 December 2020

Anonymous user

You would have to strip the Lower part of the roof back to be able to get a good secure fixing to the wall plate to meet structural guidelines. Hope this helps

Answered7 January 2021

JBS Development & Construction Ltd

No reviews yet

Pinner

If your going to add a rafter to the existing and put it from wall plate to the ridge with the correct cuts then in my opinion you need to strip the roof.However if your putting steels in and are building a dwarf wall you can ask your engineer if you can add the new rafters to go from the ridge to just past the dwarf wall and then they will be supported on the dwarf wall.If he allows this you can then do that without stripping the roof.

Answered9 January 2021

Joycentric

Rating: 5 out of 5

Wigan

Its very hard to get something as long as the rafter to go down to the wall plate after all the rafter is longer than the inside roof space. What I would do is butt the top end to the ridge like the existing rafters but then stop them before they get to the wall plate. The dwarf walls will split the span of the old rafter so that the bottom section of rafter does not require the increased size. Its difficult to explain but if you run this answer by your engineer he will confirm that this will be acceptable.

Answered10 January 2021