INJECTION DAMP PROOFING FROM OUTSIDE

surreygirl

New Member
Hello All,

I own a flat where we are having the whole of the outside render removed and re-rendered as it has become porous over the years. Also whilst the render is off I would like to have a damp proof injected to help witht he damp. I know a lot of people are skeptical about damp proof injections so I would just like a few opinions.

My flat is a semi basement. With one wall at the back with earth up against it. So the wallks that can be done would be those do not have earth pile up against them. One of the walls is an internal wall and that has already been injected. The neighbour had that done.

The Project Manager has suggested I tank the flat. All very well but there is a tenant in it at the moment and the wall where there is earth has been tanked.

The other issue with tanking my walls is that there will be two walls which are water proof and the damp will rise up into the upstairs flats and cause damp to their flat.

I need to make my flat as water proof as possible. It is not costing a great deal under 1 thousand and it will at least, I think, stop rising damp in the flat.

Looking forward to your suggestions.
 

surreygirl

New Member
Where else woulf it go then if there are two sides which are water proof with rising damp!! Damp can only go up surely.!!! I do not know, but I read somewhere that if you have two walls that are water prooved then the damp will have to go.

The problem is that the render has been pourous for over 12 years and the company - freehold company - have failed to do anything and the brick work is soaking wet and in some cases non existent. I have seen some of it. It looks horrendous!! So where will all that water go if the there are two walls which are water proved added to which I have a tenant in it and so cannot tank the whole flat at the moment so am trying to make it as water proof as possible.

They are due to start the work soon and so I need to know if a DPC would be good and if so I need to convince the Managing Agent that I should allow the company I have selected to put in a DPC from the outside!

Thank you for all your help
 

madmonk

Private Member
No it doesnt that is a myth. However having said that with the brickwork being so wet and damp coming up where is the damp going to go which is
No it doesnt that is a myth. However having said that with the brickwork being so wet and damp coming up where is the damp going to go which is already in the brickwork!!
It sounds more like penertrating damp wnich needs looking at maybe someone close to Surrey could take alook
 
Water will find it’s way in if it can. Anything below ground level you want to have a proper damp proof system in place. Injecting into the damp course will only prevent rising damp. Your basement below will still have penetrating. Tenant needs to move out and put a sump in the floor, no solid plaster on the walls. You pay a grand and it will be wasted,
 

surreygirl

New Member
Do you have to re render the outside .
Why not just repoint it , you could use a lime render to allow breathing also

Yes the whole house is being rendered. I have a flat in a Victorian building made up of six flats. There is a lot of penetrating damp. Not sure if it has rising damp but to be on the safe side. I thought I would have a damp course put in whilst the render is off.

Sorry for late response I thought replies would come into my email account. But obviosly not.

Thank you for your response.
 

surreygirl

New Member
Water will find it’s way in if it can. Anything below ground level you want to have a proper damp proof system in place. Injecting into the damp course will only prevent rising damp. Your basement below will still have penetrating. Tenant needs to move out and put a sump in the floor, no solid plaster on the walls. You pay a grand and it will be wasted,

The flat isnt really below ground because all the earth has been taken away.

What I was trying to do is make it as water proof as possible and put in a damp proof course from the outside whilst the render is off! Is that not a possibility then. It would stop any rising damp. Hopefully!!
 

Attachments

  • 2017-09-13 17.22.39.jpg
    2017-09-13 17.22.39.jpg
    904.4 KB · Views: 62

surreygirl

New Member
Water will find it’s way in if it can. Anything below ground level you want to have a proper damp proof system in place. Injecting into the damp course will only prevent rising damp. Your basement below will still have penetrating. Tenant needs to move out and put a sump in the floor, no solid plaster on the walls. You pay a grand and it will be wasted,

Thank you for your reply. Sorry I have only just seen this as I thought replies came to my email inbox. It is difficult at the moment for a tenant to move out as she has nowhere to go and I thought that as they are removing the whole of the render I would put in a damp course at the same time from the outside to help with the damp.

So you think that it will be wasted then!!
 

surreygirl

New Member
Just to say we have a surveyor in and taking all the render off was his advice as the whole of the render is no longer water proof and his advice was to remove all the render and re-render!! The surveyor is not attached to any company. We got an indepentant report.
 

surreygirl

New Member

Yes we have had a survor in and I have penetrative damp. However I thought that as all the render was coming off and re-rendering the house. I would take the opportunity to put in a DPC from the outside. Not costing much and would make a difference. Hopefully!!
 

surreygirl

New Member
If it's a cavity wall cleaning out the cavity to below ground level will help.
Have a chat with these about the rest.

It isnt a cavity wall. The building is Victorian and the walls are about a foot thick. In some places more.
 

surreygirl

New Member
Use lime then ? No cement is a must !

The builders will be deciding what to use lime or cement for the render along with the project manager.

What I want to know is should I put in a damp course from the outside because they are not going to do it!
 

ChrispyUK

Well-Known Member
The builders will be deciding what to use lime or cement for the render along with the project manager.

What I want to know is should I put in a damp course from the outside because they are not going to do it!

you need to find out what the issue is. House I bought last year had ‘damp issues’ and at some point previously some c**t has injected it, hacked internal plaster off up to 1m and replaced the floor boards and joists downstairs which are rotten again because water was getting under the floor.
 

surreygirl

New Member
you need to find out what the issue is. House I bought last year had ‘damp issues’ and at some point previously some c**t has injected it, hacked internal plaster off up to 1m and replaced the floor boards and joists downstairs which are rotten again because water was getting under the floor.

Yes we do know. We have had a surveyor in and he wrote a long report. The render is not water proof and needs to be replaced.

What I am trying to find out is if a Damp proof course can be put in from the outside. My flat is a semi-basement and so I was taking the opportunity to put in a DPC whilst the render was off and after the brickwork has been replaced.

I only have one floor. It is one bed semi basement or garden flat.

We have rotten joists. Next doors ceiling fell in. Mine hasnt yet.
 

JML

Member
If you have two walls which are waterproofed (tanked) then you can can get damp rising ,because it can’t evaporate from the wall (chimney effect) ,unless vapour permeable tanking system. Injecting a chemical DPC at the flat above is unlikely to do any good. (a waste of good money l would say).
 

surreygirl

New Member
If you have two walls which are waterproofed (tanked) then you can can get damp rising ,because it can’t evaporate from the wall (chimney effect) ,unless vapour permeable tanking system. Injecting a chemical DPC at the flat above is unlikely to do any good. (a waste of good money l would say).

Hello there, no my flat is not tanked yet, but the next door flat is tanked. However we are having builders in to take off the render and re-render as it is no longer water proof.

My question is this. Can I put in a damp proof course in my own flat instead of tanking the flat. I have a tenant in it and it is not convenient, but the Agent is suggesting that I tank my own flat just as next door has done.

However I thought just as you have said that if I tanked and the outside render is also water proofed then the water will rise up.

It is my own flat that I want to put in a damp proof course from the outside because it is a good opportunity for me to try and and make my flat as water proof as possible.

The flat above does not belong to me and I have said to the Agent if I tank then the water will rise up to the flat above.
 
Thank you for your reply. Sorry I have only just seen this as I thought replies came to my email inbox. It is difficult at the moment for a tenant to move out as she has nowhere to go and I thought that as they are removing the whole of the render I would put in a damp course at the same time from the outside to help with the damp.

So you think that it will be wasted then!!

Unless you combine the external work with doing the internal then you’ll never fix the damp problem. It might be inconvenient for the tenant to move out but if you want it done properly then that’s what needs to happen.
 

JML

Member
Yes you can inject your wall. Perhaps with a water based system as it diffuses into damp mortar better than trying to displace the moisture like a spirit based system. ( inject the mortar line not the brick). A better system of course is inserting a physical dpc system ,( probably not practical in your situation).

the residual moisture within the walls could take years to evaporate, its drying path will mostly be to the internal surface, when moisture is evaporating from a wall it can leave salts within or on the surface can be the source of secondary dampness in that they can be hydroscopic, attract moisture from a damp atmosphere and some liquify on the surface. So, you may have to look at installing a dehumidifier.
 

Swplasterwork

New Member
If it’s not a cavity wall. It needs to be lime rendered.
It’s more than likely your surveyor is not accredited or experienced enough to be surveying buildings of this age.
Avoid the damp course at all cost..
Lime render externally.
Ventilate the buildings if you are not able to lime plaster internally through out.
 

surreygirl

New Member
Yes you can inject your wall. Perhaps with a water based system as it diffuses into damp mortar better than trying to displace the moisture like a spirit based system. ( inject the mortar line not the brick). A better system of course is inserting a physical dpc system ,( probably not practical in your situation).

the residual moisture within the walls could take years to evaporate, its drying path will mostly be to the internal surface, when moisture is evaporating from a wall it can leave salts within or on the surface can be the source of secondary dampness in that they can be hydroscopic, attract moisture from a damp atmosphere and some liquify on the surface. So, you may have to look at installing a dehumidifier.

That sounds good. However the damp proof chap is going to inject a DPC but from the outside. I will need to speak to him about that I think.

My tenant does use a dehumidifier already.

Thanks for that reply.
 

surreygirl

New Member
If it’s not a cavity wall. It needs to be lime rendered.
It’s more than likely your surveyor is not accredited or experienced enough to be surveying buildings of this age.
Avoid the damp course at all cost..
Lime render externally.
Ventilate the buildings if you are not able to lime plaster internally through out.
I do not know what render they are using for the outside. It is down to the Managing Agent whose workman are carrying out the work.

I will ask what render they will be using. So thanks for that.

Can I just ask why I should avoid the damp course. I though that it would make the walls more water proof as the walls are so think. I do have penetrive damp as well, but I just thought that I would put in a DPC whilst the going is good and the render is removed from the outside of the building!!

Are DPC's no good then!
 

surreygirl

New Member
If it's a cavity wall cleaning out the cavity to below ground level will help.
Have a chat with these about the rest.

I am just about to have a chat with this company. I prefer the membrane even if you lose a bit of space. tanking is messy to say the least. So thanks for that link (y)
 
Top