DPC help please.

[Steve200000023]

Hello there.

We purchased our house 2 years ago that was identified to have areas of damp, and I am now looking to see what I can do to rectify the situation.

On inspection, the house has solid floors, but the DPC is 2 brick courses below the internal finished floor level!? With the top of the air bricks level with the internal floor, I have read that people can install concrete floors to replace timber joist!? which would explain why the DPC level is correct for a timber joist floor and not for the replacement floor.

Q1. If I was to buy a DPC injection kit, would I go the 2 courses higher than original DPC so that it would now be level with the current solid floor.

Q2. If I lay a new patio with aco drain against house, could I go within the recommended 150mm of original DPC, also taking into account that a new injected DPC would potentially be installed at a new higher location.

any guidance/advice on this would be massively appreciated. I appreciate how busy we all are and your time given to this is amazing.

thanks in advance.

 

[Jord86]

So where is the actual damp showing itself? Post up some photos.

 

[Steve200000023]

Hello there.

We purchased our house 2 years ago that was identified to have areas of damp, and I am now looking to see what I can do to rectify the situation.

On inspection, the house has solid floors, but the DPC is 2 brick courses below the internal finished floor level!? With the top of the air bricks level with the internal floor, I have read that people can install concrete floors to replace timber joist!? which would explain why the DPC level is correct for a timber joist floor and not for the replacement floor.

Q1. If I was to buy a DPC injection kit, would I go the 2 courses higher than original DPC so that it would now be level with the current solid floor.

Q2. If I lay a new patio with aco drain against house, could I go within the recommended 150mm of original DPC, also taking into account that a new injected DPC would potentially be installed at a new higher location.

any guidance/advice on this would be massively appreciated. I appreciate how busy we all are and your time given to this is amazing.

thanks in advance.

below are some photos showing various locations.

the damp near the grey door I’ve been told is because of the concrete skirt that is bridging any DPC there is!?

 

[Steve200000023]

So where is the actual damp showing itself? Post up some photos.

So where is the actual damp showing itself? Post up some photos.

Hi. I’ve posted a few photos. Cheers

 

[qwas123]

OP,
1. So you have suspended floors and solid floors?
2. You also appear to have cavity walls.
3. DPC's go in your walls - & a DPM (a membrane) goes under the solid slab.
4. DPC's should have been installed at least a course above any ground level, & just below the joists seated in wall pockets.
5. You might benefit from opening up by removing six bricks to view the cavity for any cavity bridging?

6. The skirtings - of any material - must be removed.
7. Hack off back to brick all damaged plaster to a height of at least 1000mm - or at least 300mm above the highest points of contamination.
8. Do the walls have CWI?
9. The finished floor in the last pic might have damp damage near the wall?

 

[Steve200000023]

OP,
1. So you have suspended floors and solid floors?
2. You also appear to have cavity walls.
3. DPC's go in your walls - & a DPM (a membrane) goes under the solid slab.
4. DPC's should have been installed at least a course above any ground level, & just below the joists seated in wall pockets.
5. You might benefit from opening up by removing six bricks to view the cavity for any cavity bridging?

6. The skirtings - of any material - must be removed.
7. Hack off back to brick all damaged plaster to a height of at least 1000mm - or at least 300mm above the highest points of contamination.
8. Do the walls have CWI?
9. The finished floor in the last pic might have damp damage near the wall?

cheers, some great advice there. The main query I have is that it seems the existing DPC is 2 courses lower than my Finished floor internally!. If I install a new DPC by injected cream etc, would this effectively become the new DPC and would it work etc!? Many thanks.

 

[qwas123]

A new DPC in the cavity wall outer skin of bricks wont do much - esp if the cavity is blocked & bridged.
"DPC injected cream" is a bit hit and miss - but a DPC above the level of the joist seats is useless.
Why not post larger context pics of the ground level around your house?

 

[BuildingMad]

Your problems are not necessarily related to the replacement concrete floor.
It could have been carried out properly with a DPM starting below the wall DPC & returning up the wall, or a separate vertical DPM, with concrete & screed.
What age is the property.
Are all your floors concrete.
Stretcher bond, while mostly indicating cavity wall, could be a solid wall. Are you able to confirm.
Do you know the reason for coating the brickwork as it could be an indication of stopping water penetration, especially in a solid wall or a cavity wall with bridging problems.
Where is the DPC level in relation to the outside concrete you show in a photograph

 

[Steve200000023]

Hi. Thanks for the advice. here is some further info/photos.

The survey dated the house circa 1950
The downstairs has solid floors with an asphalt coat I believe.
The main 4 walks have cavity, I believe the inner wall with the concrete skirting I believe to be a single brick wall.
the photos below show the existing DPC level and the level of the internal floor. The photo of the front corner show the drive way at the same level of the DPC, this was done many years ago apparently to level the drive with the neighbours, the path leading to the porch is lower with a drain for surface water, but I don’t think it does much liking at the damaged bricks for water. The house has got planning permission for a small garage/porch extension. I’m hoping to get this done soon in order to protect this corner of the house.

 

[qwas123]

OP,
Air bricks can be seen at two different levels but do I understand you to claim that all the suspended floors have been replaced by solid floors?
Given the damp damage shown then its possible that the solid floors bridged any DPC's in the walls?
You could insert "damp cream" in the perps & beds just above the FFL & hope for the best.
There are other possibilities for why things are as they are.

Your pics show a pipe emerging from the "driveway" concrete?
The Pvc door needs re-sealing and having an extended sill fitted.
Some of the historic re-pointing has failed & needs doing again - rake out to 25m.

 

[Steve200000023]

OP,
Air bricks can be seen at two different levels but do I understand you to claim that all the suspended floors have been replaced by solid floors?
Given the damp damage shown then its possible that the solid floors bridged any DPC's in the walls?
You could insert "damp cream" in the perps & beds just above the FFL & hope for the best.
There are other possibilities for why things are as they are.

Your pics show a pipe emerging from the "driveway" concrete?
The Pvc door needs re-sealing and having an extended sill fitted.
Some of the historic re-pointing has failed & needs doing again - rake out to 25m.

OP,
Air bricks can be seen at two different levels but do I understand you to claim that all the suspended floors have been replaced by solid floors?
Given the damp damage shown then its possible that the solid floors bridged any DPC's in the walls?
You could insert "damp cream" in the perps & beds just above the FFL & hope for the best.
There are other possibilities for why things are as they are.

Your pics show a pipe emerging from the "driveway" concrete?
The Pvc door needs re-sealing and having an extended sill fitted.
Some of the historic re-pointing has failed & needs doing again - rake out to 25m.

Thank you for you advice, much appreciated.

The pipe in the photo I believe was installed when the drive height was increased to make a makeshift drain for surface water, I believe it goes under the concrete and joins onto the soil pipe.

The air bricks are on the same line, with the exception of a larger air brick which is a couple of courses higher as this is under the downstairs toilet that is a couple of steps up from the ground floor.

I do plan to rake out damaged/failing mortar and redo before I entertain the damp proof injection.

I think I will try the DPC cream at floor level as I have read a few articles saying that is the best practice, but like most things there’s a 50/50 split on whether it works or not.

The side single storey extension (old coal store/outhouse) with the UPVC glass/door, I’ve been advised there’s no DPC here, so plan to strip back to brick, tank the walls the lay a membrane and pour a new concrete floor to being just below same height of main house floor then top up with a self levelling screed.

Lots of jobs to do it seems, take them one at a time.

again I appreciate you taking the time to share you knowledge on these issues.