Chemical damp proof holes externally?

[ezza]

Hi all,

I’m new here and have been searching to see if I can find an answer so apologies if this has been answered!

We recently bought a ground floor flat which we were aware had some damp issues from our level 3 survey that we did when purchasing the property. We mistakenly got a free damp survey also which now after reading was a mistake as I’ve learnt they just try to rip you off!!

A bit about the flat - it’s ground floor and has been rented for the past at least 20 years with no care taken of it and the more we look the more we can see cheap jobs have been done, most probably landlord specials!

I’ve started to look into the damp issue now to try and at least work on some before the colder months come in. I’ve noticed in the garden these holes that are not filled in and look to have been there for a while - are these old chemical damp proof holes that haven’t been filled in? If I fill these in will that at least relieve the walls / bricks of some water getting in from the rain etc?

There are other issues with the property so starting with the big issues first! See the photos attached - I took these after the huge downpour as you can see the water is getting above the holes.

Any advice is appreciated! I also know I could be completely wrong lol!

 

[Lacan07]

Hi all,

I’m new here and have been searching to see if I can find an answer so apologies if this has been answered!

We recently bought a ground floor flat which we were aware had some damp issues from our level 3 survey that we did when purchasing the property. We mistakenly got a free damp survey also which now after reading was a mistake as I’ve learnt they just try to rip you off!!

A bit about the flat - it’s ground floor and has been rented for the past at least 20 years with no care taken of it and the more we look the more we can see cheap jobs have been done, most probably landlord specials!

I’ve started to look into the damp issue now to try and at least work on some before the colder months come in. I’ve noticed in the garden these holes that are not filled in and look to have been there for a while - are these old chemical damp proof holes that haven’t been filled in? If I fill these in will that at least relieve the walls / bricks of some water getting in from the rain etc?

There are other issues with the property so starting with the big issues first! See the photos attached - I took these after the huge downpour as you can see the water is getting above the holes.

Any advice is appreciated! I also know I could be completely wrong lol!

View attachment 14395

View attachment 14396

View attachment 14397

Yes that looks like a chemical injection.

That concrete plinth might need to be hacked off, it may have originally been conceived to protect the wall from being splashed by the rain but it could be providing a bridge for moisture in the ground to jump the DPC. Those concrete plinths can be very troublesome and are generally a bad idea.

Can you see a DPC at all? I suspect the external ground is too high hence the reason the plinth was created. You might need to lower the ground levels to prevent the wall from being splashed in the future.

You can fill the holes and repoint those worn mortar beds with NHL 2 or 3.5. It comes in powder form, just add water and follow the instructions. You'll soon get the knack. If appearances are important to you and you want to achieve sharp edges I would advise getting some brick tape and masking the face of the brick before applying the lime mortar. Keep the mix on the dry side, lime does stain and its very easy to make a dogs diner of it.

 

[jamest]

From the picture, it looks to me as though there is a chemical injection 'dpc' in the mortar bed two courses of brick above the top of the cement layer - those little daubs of cement in a line are covering up the injection holes. So why the additional injection dpc lower down on the cemented bit? At what level is the internal floor?

Anyway, the best thing to do with that cement is get it off and do what Lacan suggests. That won't stop water splashing up the wall when it rains though - it would be sensible to strip the hard surface back 40 cm or so from the wall and put gravel or grass or something there to reduce splash.

 

[ezza]

Yes that looks like a chemical injection.

That concrete plinth might need to be hacked off, it may have originally been conceived to protect the wall from being splashed by the rain but it could be providing a bridge for moisture in the ground to jump the DPC. Those concrete plinths can be very troublesome and are generally a bad idea.

Can you see a DPC at all? I suspect the external ground is too high hence the reason the plinth was created. You might need to lower the ground levels to prevent the wall from being splashed in the future.

You can fill the holes and repoint those worn mortar beds with NHL 2 or 3.5. It comes in powder form, just add water and follow the instructions. You'll soon get the knack. If appearances are important to you and you want to achieve sharp edges I would advise getting some brick tape and masking the face of the brick before applying the lime mortar. Keep the mix on the dry side, lime does stain and its very easy to make a dogs diner of it.

From the picture, it looks to me as though there is a chemical injection 'dpc' in the mortar bed two courses of brick above the top of the cement layer - those little daubs of cement in a line are covering up the injection holes. So why the additional injection dpc lower down on the cemented bit? At what level is the internal floor?

Anyway, the best thing to do with that cement is get it off and do what Lacan suggests. That won't stop water splashing up the wall when it rains though - it would be sensible to strip the hard surface back 40 cm or so from the wall and put gravel or grass or something there to reduce splash.

Thank you both for the response! Makes sense as to why the water shows on those bits then if it’s splashing up from the hard floor surface!

We are planning to do a side extension hopefully next year on this bit so this should take care of the concrete on the side of the property so hoping to just for now minimise a miserable winter with damp coming through. I’ll try filling the holes - this is also near a section of the property that we won’t be taking down so it’s good to know that for that area the best would be what’s been suggested for a start!

Haven’t had a chance to look below the floor boards yet but these holes are below the floor as it’s a bit more raised inside. I think we will take up a floor board or two and see what is going on inside as well and see if we can see the DPC.

 

[Lacan07]

Thank you both for the response! Makes sense as to why the water shows on those bits then if it’s splashing up from the hard floor surface!

We are planning to do a side extension hopefully next year on this bit so this should take care of the concrete on the side of the property so hoping to just for now minimise a miserable winter with damp coming through. I’ll try filling the holes - this is also near a section of the property that we won’t be taking down so it’s good to know that for that area the best would be what’s been suggested for a start!

Haven’t had a chance to look below the floor boards yet but these holes are below the floor as it’s a bit more raised inside. I think we will take up a floor board or two and see what is going on inside as well and see if we can see the DPC.

If youre planning to build an extension there I wouldn't bother filling the holes then, one winter won't hurt. Its difficult to get mortar into small holes anyway unless you were planning to fill with silicone.

 

[jamest]

Given that those holes are below your internal floor level, it seems odd to have injected a dpc there. If the floor is suspended, perhaps the holes were drilled for ventilation . .. do they go right through? Worth checking before you do any filling!

 

[ezza]

Given that those holes are below your internal floor level, it seems odd to have injected a dpc there. If the floor is suspended, perhaps the holes were drilled for ventilation . .. do they go right through? Worth checking before you do any filling!

I did think maybe they were for ventilation - I tried to have a look yesterday but seems they are just filled with dirt but I will try and poke something through to see if it goes far or not.

I did have a look through where one our air brick vent would be (one of them is completely off so was able to shine a torch in) and it seems the ground inside is about 30cm below the hard surface in the garden so I am thinking this might be the issue? If there were a dpc then that outside section would most probably be well above it!