Best Way To Stop Damp

[Belboz]

Scenario is external walls with no DPC. No cavity - believed they are just built 2 bricks thick. Most of the wall is rendered but the lower portions are open i.e. the brick is facing the weather.

What is the best solution to prevent wet/damp getting in through the external brickwork? DPM? Bitument Paint??

Any ideas welcome.

Thanks,

B.

 

[jeds]

Air flow and ventilation will sort most of it out.

 

[Belboz]

Thanks John but there is damp getting through hence why I want to be able to prevent it.

It may just have been the amount of rainfall but I want it sorted in case of any future issues.

 

[stuart45]

Is the pointing in good condition?

 

[Belboz]

Pointing is fine.

I believe the issue is that the rain is seeping through the bottom bricks because there is no DPC to stop it rising.

 

[tony1851]

Pointing is fine.

I believe the issue is that the rain is seeping through the bottom bricks because there is no DPC to stop it rising.

You are confusing the two; rain is penetrating damp, while rising damp is, well, rising damp from the ground.
Are the bricks at the base particularly soft?

 

[Belboz]

Sorry for getting this wrong. Perhaps I haven't explained fully.

The external wall is at the front of the house. It has no DPC.

The carport (which is basically a large concrete slab) runs with the fall towards the wall (yep - I know it shouldn't but the eejits who built it in the 50s obviously didn't care)

This wall is rendered but only to a point about 8 inches above where the carport stops. The bottom 8 inches is just plain brick.

A few years back, someone must have seen the issue with the carport and has removed a section of concrete in front of the exposed brick wall which has then formed a ditch about 2 feet deep. This ditch is filled with pea shingle.

So, in effect, rain runs down the carport into this ditch filled with pea shingle. Rain also gets directly on the shingle from above. The now wet shingle is directly against the brick wall and the damp is getting through.

My intention is to dig out all the shingle and resolve the issue by some means - whether this be by bitumen paint or a dpm or whatever.

If that isn't going to work then I will have to consider re-filling the ditch with concrete and ensuring it is shuttered above the carport so that water will not run into the ditch and will run backwards off it.

I hope that makes sense and YES pics would have been an idea!!

SORRY.



B

 

[Joe Malone]

Adequate wall bass ventilation... Ensure that external floor levels are 200mm lower than internal finished floor level and you don't need a physical DPC. Thousands of buildings do not have a DPC and perform perfectly well without them so long as this rule is followed.

 

[Belboz]

Understood joe but that rule hasn't been applied when they built the place because the carport which previously met the base of the wall was HIGHER than the internal floor level.

It's been chopped away (as I said) but I now have the issue of damp getting in and wanted to know the best method to solve the problem.

Thanks for the info though..

B

 

[tony1851]

As jeds and J.M. have suggested, proper ventilation may be the solution here.

Why not take out all the shingle (it will probably be keeping the wall damp anyway, reducing the ability of the wall to air off) and give the wall a few weeks to - hopefully - dry out.

Better to try something simple and cost-free like this, before embarking on more complex measures.

 

[Belboz]

Thanks Tony.

I will try that first and see how we go.

 

[ziden]

I used to own a house built in 1670 in random stone with random rubble back fill, walls were about 2½ ft thick. So, long before dpc's were thought of and a potential dampness nightmare.

Here's what I did, rather similar to your proposal in some respects.
I dug a trench, tight to the walls right around the house about 2ft deep and 18" wide, laid to a fall obviously. I put perforated land drainage pipe in the base of the trench, leading to a soakaway.

The trench was back-filled with 3/4" CLEAN filter media (stone). (Definitely don't use pea gravel) I specified that most emphatically to the quarry, who obviously took it on board because the first thing the driver asked on delivery was "is this clean enough?"

The principle here is that the filter stone is too knobbly to have many contact points, so water cannot pass across the "trench" and has to go down - to the base land drain. Being clean, there is no fine stuff to aid water movement across.

Then to cap it all off, because of the random stone construction of the walls, I specified an internal electro-osmotic damp proof course. Funny, the "specialist damp proofing installer" hadn't got a clue what I was talking about. I said, "let me explain . . . "

But it was a dry old . . . very old, house.
Food for thought for your solution?

 

[Belboz]

Thanks very much for that ziden.

Definitely food for thought regarding the trench fill etc.

B

 

[Joe Malone]

Thanks very much for that ziden.

Definitely food for thought regarding the trench fill etc.

B

A French drain is an option but bear in mind that they get silted up every 12-24 months and need regular maintenance that most people don't bother with. Believe it or not I have a patent pending on a building product that would solve your problem.