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Structural question


I'm doing some renevations to my property and there is a 3 x 9 inch timber across the lounge supporting a brick wall above. The joists of one floor above also rest on this timber. Timber is about 3.5 metres long.

As the picture shows, this timber is resting on half a brick sticking out of the wall. I would like to secure this so I am thinking of extending the brick wall by half a brick so that the timber is supported better. Do I need to support the timber with acrow props whilst I extend the wall. There is also a wood lintel in that brick wall. Should I remove it or can I just leave it and extend the wall?



1 Answer from a MyBuilder Architectural Designer

Best Answer


Provided the timber beam sits on up to 4 inches of solid wall then the bearing itself is adequate. However, I have done a quick structural check of the beam based on the information you have provided. I have assumed the wall it supports above is single skin brick or block with a height of 2.3m, and the beam is Grade C24 (high grade) standard off-the-shelf. I have also assumed the total length of the joists supported above is approximately 3m and it supports half this load, i.e. 1.5m of floor. The beam seems to be structurally inadequate based on the current British and European standards. It may have been installed by a builder without proper structural design and/or Building Control approval. That does not mean the beam will fall down - it has been there for a while. Note that current design standards apply a good factor of safety to structural materials.

As the beam appears not to have the required strength, You should prop it during any proposed works. Increasing the bearing by extending the wall will reduce the span and therefore increase the structural capacity. Securing it with a concrete surround within the wall (or other proprietary product) will also increase the structural capacity. I will also advise you to have the beam properly checked by a structural engineer and strengthen it if necessary, particularly as it is supporting critical loads –floor, wall, etc. You may bolt a steel plate to it to make it a ‘flitch beam’. This will likely give it the required structural capacity. I am not sure why you would want to remove the lintel. It is supporting the wall above the door opening.




Answered 24th Jan 2015

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