Damp, drains and bay windows

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Cheshire
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Hi,

I have a damp drainage issue with my home, recently purchased but we know what we where buying (the survey confirmed what I suspected), joists are rotten in the front room around the bay window.

I'm 99% sure its all down to the recent driveway. Please have a look at the pics, its been raining today and you can see water forming puddles around the building. You can also see water which is channeled around the bay window (as it is on a slope) but as it goes passed the cut off airbricks it drains through onto the subfloor. As you can see we have a puddle under the floor today after a couple of hours rain.
Two air bricks on this side of the building either side of the bay window. These are two brick's deep and what looks like an original doc is level with the top of the air bricks. Pointing has mostly gone at ground level.
I'll scan in the damp survey diagram later today. His finding was that the high level of the ground level was causing the damp issue, sub floor ventilation must be increase and ground level lowered.

Now I appreciate that the ultimate solution may be to lower the whole driveway but I'd like to try a less drastic solution first, I'm thinking of removing the last course of bricks on the driveway and installing a concrete chanel (so ground level would be 2 bricked down where it meets the houses) which would drain into existing drains. Repointing and reconfiguring the airbricks, my questions are:

1) Am I on the right track?

2) How am far should I dig down and backfill with concrete?

3) I'm thinking of changing the two double air brick's to four single so the would be above ground and 'splash level). How do I calculate the required number of airbricks? Also my house has airbricks on three sides, I thought this was a bad idea? Should I block off the sides?

4) I think the house is lime mortar (1929), should I repoint in lime? If im pouring concrete do I need to repoint below the level of the concrete? If so how long should I wait for the pointing to dry before installing the concrete?
For now im only concentrating on the front, next job will be similar system for the side then the back will be done in conjunction with an extension in about 18 months.

Appreciate the advice in advance, thanks all
 

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I cant follow the mass of above detail but in brief, raising the air bricks is one possibility but installing ACO drains would probably be the best solution.
Where is the DPC?
What is the wood post supporting, are there any more earth to wood contacts?
The post will have to go - its fungal damaged.
Can you post photos of the rotted bay joist tails?
Are your walls solid?
Lots of air bricks is good, keep them cleaned out - insert a new air brick on the left side of the bay.
Are there any damp signs indoors?
 
thanks for the reply,

wad thinking ACO drain but couldn't find any curved ones, are there any prefab drains that are bendy to go around the curve of the window?

DPC is in line with the top of the airbrick,

post is supporting the floor, this is all rotten with a high moisture reading, I cant see any more posts but there's lots of small walls under the floor. I'll only find out when I start replacing the floor.

pick below - is this what you mean,

yes the walls are solid, 2 bricks thick with no cavity.

Yes there are high moisture reading in the plaster at low levels around the front of the house,

thanks again
 

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The gulley grill has a circular cut-out. Remove it and drop the down pipe into the cut-out just below the grill. A 90 or a 45 & a stub of pipe glued together will work. Doing this will eliminate the swirl of water soaking the wall.

I dont know of any curved ACO but its probably out there. "pavingexpert.com" are a good source of groundwork knowledge.

If you cut the paint seal & remove a length of skirting on the high moisture wall & examine the wall and the back of the skirting you might see any signs of salts or decay.

Dont move the air bricks - go with the drainage proposal of some kind.
 
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