Bay Window Footing/Foundation

[crisalex]

Hello!

Following increased readings of moisture on the internal side of the bay wall, a damp specialist has flagged raised ground levels on the exterior and recommended that the bricks at the base of the bay window are exposed and a french drain / gravel is installed around to protect the brickwork. Upon digging no bricks were found on the external side at the base, and it appears that instead there is (was...) cement which is crumbling, for at least the width of one course of bricks. It is unknown if the cement runs for the full width of the wall or how the wall is supported.

We would like to ensure the wall is properly supported and necessary repairs made before installing the french drain, as the cement base has crumbled away in places leaving the lowest bricks unsupported.

The concrete plinth on top of the bricks was in really bad condition, and essentially crumbled away from the house; the builder has since redone the concrete plinth [vs.

We're wondering what's our options for addressing this:
- do we need to add the bricks on top of the existing soil & get them to support the existing brick course?
- do we need to add some kind of foundation all around to support all these bricks?

Also looking to understand what this "foundation" should look like for a mid-terrace Victorian house - as can't really find much online about this!

Previously there was a hairline crack in the bay window (you can in a photo where the the bars were drilled into the wall) - for which we have been advised to install 3x Helibar to tie back the bay window to the main house structure, but we are now wondering if the problem all along were these missing bricks/crumbling bay window foundation.

I've attached as many photos as I had, but can always take more!

Thanks!

 

[tomm12]

If you google "images of Victorian foundations" you will see a number of stepped brick foundations.

Where you've already been digging you could dig a bit deeper, about 100mm or so then clean soil off the bricks and post new photos.
But I suspect what you show of the foundation is all you've got?
Eventually you could replace all perished bricks one or two at a time?
I dont see any concrete only bricks rendered over.
You have a solid wall and render thats doing nothing but attracting damp. The new render is like a thin finish thats been skimmed over an existing render, been painted(?) & is now flaking?

Can you show where the bay dpc is, and where the floor level is? I think the plinth render is bridging both the dpc and the interior floor?
If it is then its possibly whats causing your interior damp issues?
If the whole front of the house has a rendered plinth then there's a possibility of more interior damp?
Why was the wall was rendered with that high plinth in the first place? Depending on the state of the bricks under the render my choice would be to remove all the render?


Your photo 103458 shows what I suppose is where the "bars were drilled into the wall"?
When you mention "tie back", Is the bay pulling away from the main wall?

There's one air brick. Its not enough, air bricks should be on three sides of the bay, and vent below the floor.
Have you looked under the floor & examined the joists. They could be rotting.
Could you do photos of the interior damage & the bay floor and skirting?

The down pipe is going into an overgrown, damaged gulley. Have you removed the foliage, cleaned out the gulley, and made sure its not leaking?
Is the bay single story? Is the down pipe coming from the bay gutter and/or the main roof gutter?

 

[^woody^]

Was there an actual raised ground level - ie breaching the DPC? Or were the readings misinterpreted and actually condensation related?

Is that render up the wall new/renewed and part of the attempt to solve the problem?

You really don't want to mess with the foundation or increase the ground water level balance if there is no existing problem with the structure, as you may make one!

If the ground level was too high, then you would normally have had a damp problem for as long as it had been too high. If the damp was recent, then it would normally be due to something else, ie something changing or becoming defective.