Bressumer Beam & Bay Window Investigation Necessary?

[Jopper999]

Hi All,

My house is a classic 2 up 2 down victorian semi built in 1904.

It has a front single story bay window.

A recent sellers survey suggested "Concern that the timber bressummer beam behind the front bay construction has substantial rot and decay. Distortion noted both around the window and distortion has extended to the bedroom window above. Expected water ingress to the bay beam."

I have attached a PDF of images from the front outside and the bay window sills inside where there visibly clear drooping. Both window sills of the flanking windows drop down (from the centre) as the picture shows. Overall one could argue that the top frames of these windows drop in the same way but only by 1/2 cm max. Minor (not even a mm) superficial crack above top right window sill on ground floor and above left window top floor. Low damp meter readings all around windows on the inside. Wooden window frames on the outside looking a bit iffy, so superficial rot.

Outside looks OK, nice and 'square' and all in all structures appear level.. One minor middle crack in right hand window sill.

A structural engineer told me that he can't see anything indicating a real problem with the Bressumer beams and that we may just be witnessing the bay window settling in a shallower foundation in the house's early years. However, he said the only way of knowing is to open up and look at the beam in situ. The sill issues I mentioned above have been like that since 1997 when we moved in. Nothing I can see has changed since then either.

I have a few questions for the forum...

1. What did the house surveyors see that we may have missed? Just the dropping sills?
2. Based on the photos ... is access to check the beam from the ground floor ceiling (so major upheaval), from under the bedroom floorboards by the outer bedroom wall or by removing some bay window tiles?
3. Any other things to check or other ways of testing this easily?
4. If anyone has done a similar bay window beam check and replacement what was the cost?

Thanks in advance!

J

 

[malcolm]

I can see the window sill has cracked. A 1904 house ought to have been built in lime mortar which can move around without cracking but the sill is quite long so maybe some movement. It's not a structurally perfect arrangement to have a couple of upstairs windows sitting either side of a bay as it means the lintel over the bay needs to do a lot of work. The bricks between the upstairs windows will be taking load and there isn't enough space underneath for the normal 45 degrees brick corbelling to spread that load past the sides of the bay.

Fortunately you have horrible cement re-pointing. Cement doesn't move like lime so if there is any new movement you should be able to spot that very quickly when the cement cracks.

I would leave well alone. There is a roof well above the bay lintel which should be keeping water out. The one thing I would think about is replacing or complementing the cemented in tiles at the top of the roof with lead flashing to make sure water can't get into your lintel in the future. The cement flashing will crack and let water in even if there is no movement.