Improving ventilation and breathability in a damp basmenet

[columbus]

Hello, I'm new to this forum and I want to ask a question that I'm sure will have been asked before, for which I apologise in advance. I have looked at the previous posts relating to damp basements but I think I need to ask a more basic question than the ones I've seen posted here, being really new to this and having no technical expertise.

I have a basement in the front half of my house. It has a floor of fairly worn brick laid onto earth. The basement walls are painted white but I don't know how I can tell if its a breathable paint or not. There is one window that opens just below street level at the front of the basement. At the back of the house, where there is no basement, there's a cavity of about 9 inches between the solid earth and the floorboards of the room above. There's one air brick here and I keep the door to the basement open often to increase the ventilation. But - it's still too damp in the basement for it be used.

My question is - the bricks in the floor are covered with the grime of years. If that layer of grime is removed, I don't quite know how yet, and if the walls are stripped of paint that isn't breathable - and if the ventilation can be improved, is it likely that the basement will become sufficiently dry to be useable for storage. I'm in a little terrace of 1870s houses, most of which have already had their basements tanked, but we've recently been listed and I've been told that's not now an option, added to which I would much rather sort the situation out more naturally if I can.

If that might be a solution and anyone can give me an idea of how you get rid of the layer of grime I reckon is sure to be stopping the brick floor breathing, I would be really grateful. Short of scrubbing each brick with a wire brush, I have no ideas. I think it's only years of dirt that I need to get rid of.

I think I might also benefit from having more airbricks at the back of the house so that there is better airflow.

I apologise that this is rather a basic question!

Many thanks for any help anyone can give.
Columbus

 

[middi]

Hi Columbus.
first of all there is no need to apologise if you feel that you are asking a lot of questions regarding a problem, the contributors on this forum relish on akward questions, especially one relating to damp
Questions on damp are very intriguing and extremely difficult to advise on a course of action to take in order to eradicate it following forum discussions. The best you can hope for is lots of practical ideas.
The most obvious thing to do would be engage the services of an indipendant damp specialist to examine and advise on the best course of action under your circumstances.
In your case, and as you explained it, the obvious thing to do would be to increase the natural ventilation area and on extreme cases fan assistance may help. I mention extreme simply because there may be serious underlaying reasons why you cellar is very damp, all sorts of nasty ideas spring to mind such as, surface drain problems, leaking pipes in the vicinity, problem my be accentuated by you neighbours tanking their cellars and routing all the natural water dispersal drainage towards you cellar, etc, etc..
This is the reason why I mentioned the word " akward" ( although unfortunately interesting).
I am sure other contributors will offer encouraging ideas for you to thing about and draw conclusions as to what may be the best course of action to follow.

Middi

 

[Penners]

I echo what Middi has said, in every respect. Damp problems can be very difficult to diagnose on site. From a written description, even more so.

First the floor: I don't believe a layer of grime is likely to be preventing breathability too much. Nevertheless, it would be good to clean the floor. I would try to vacuum up as much loose stuff as possible, and then give it a good scrub (and I do mean scrub - not just wipe!) with detergenty water. Dry off as much as possible with old towels. You'll probably see an amazing difference.

It's very difficult to know whether the paint on the walls is breathable. You might try washing a test area - if the paint comes off then it could be limewash (which is breathable). But in a cellar it's impossible to know whether removal of all the paint would dry things out satisfactorily.

Ventilation is very important, as Middi said. Warmth too. Warm air drawn through the cellar to the exterior will be the best way to dry things out slowly and gently. But I'm afraid it's impossible to know whether, once you cease this treatment, the damp will return. All you can do is have a really good look round and see whether you can spot any obvious sources of damp.

Ultimately, if you want the cellar to stay dry, you may have to resort to a barrier method. But don't just call in a free "surveyor" (otherwise known as "disguised salesman"!) from any old "damp treatment specialists". Employ a proper specialist surveyor who will charge you for his survey and advice, and won't try to sell you a solution. That way you'll get qualified, impartial advice.

 

[MatthewC]

IIt's very difficult to know whether the paint on the walls is breathable. You might try washing a test area - if the paint comes off then it could be limewash

I'm just about to apply limewash to decorate my re-plastered house so I'm intrigued by this statement. Surely limewash doesn't wash off? It is lime putty (calcium hydroxide) which absorbs carbon dioxide from the air and so becomes (over a long time) calcium carbonate. At worst you might get chalk dust held in suspension in the washing water.

Are the bricks on the wall grimy like the floor? Does the paint flake? Are there layers? Is it glossy? Try a small amount of wire brushing - does it produce dust?

As a matter of interest, what is the state of the joists under your floor at the back? If it's all as damp as you imply I would expect that there would be some rot and possibly beetle.

Matthew
http://houseintheenchantedforest.blogspot.com/

 

[Penners]

IIt's very difficult to know whether the paint on the walls is breathable. You might try washing a test area - if the paint comes off then it could be limewash

I'm just about to apply limewash to decorate my re-plastered house so I'm intrigued by this statement. Surely limewash doesn't wash off?

I confess that I've never tried this myself, Matthew. I was relying on information that others have posted from time-to-time, suggesting that limewash can be washed off.

 

[middi]

limewash once applied and dried can be soaked with water and esily scrubbed off. ( albeit a bit persistant if multilayered applications ).
When dry I wouldnt want to brush against it with a black shirt.
That is a fact.

Middi

 

[JoceAndChris]

Allow several days for the proper cleaning of a filthy floor. I use fine grade wire wool and the Liberon stone cleaning products. Take a small section at a time and just keep scrubbing and replenishing the water!

A dehumidifier might help your basement situation. Ours was very damp when we moved in, but increasing heating, ventilation and dehumidifying has made it a useable part of the house. Good luck!

 

[Penners]

A dehumidifier might help your basement situation.

Yes, it might, provided it's really needed. The trouble with dehumidifiers is that they can in some circumstances over-dry the area. This can be deleterious to the structure and may not have a lasting effect, once the dehumidifier is removed.

 

[chapel]

Hello,

We're in the middle, or somewhere near the middle i hope, of going through a cellar refurb - so i thought'd i'd share our experience.

Last year when we moved in i had a survey by a reputable (but useless) surveyor then a few firms come to check it out. The cellar was borderline damp and hadn't been used in a while. It has a window, 3 of the 4 walls are plaster, 1 is ragstone and mud. They all suggested cementious tanking or breathable membrane.

We decided to wait and improve ventiallation and see how it fairs- so for the last year we've left the cellar door open and been opening the window when able. Have recently fitted some trickle vents above the window too. We've also stripped the thick thick thick vinyl wallpapers and removed carpets.

It's now much drier down there. Had a couple more firms look at it recently and they said the walls didnt need anything doing to them - all that needed to be done was the one ragstone and mud wall, and the area of floor butting to it, should be covered by a breathable membrane.

Over all we're much happier and it looks like the cost to make it habitable have dropped from c.£8k to c.£2k

We do still however have a humidity issue - its always in the region of 60-70%RH (which is a little high). Going to see how it goes and if it causes a problem then we'll opt for a humidity fan venting outside and set into the ceiling

Paul

 

[Schoolmarm]

Would rendering in lime and painting in limewash be a better alternative for the wall?

 

[Penners]

The cellar was borderline damp and hadn't been used in a while....We decided to wait and improve ventilation and see how it fairs...It's now much drier down there.

Good decision, Paul. And it's good to hear your experience, thanks.

 

[worms]

its always in the region of 60-70%RH (which is a little high).

We very rarely manage to get the humidity anywhere in the house below 60%! At this time of year external ambient is normally above that and with no heating on there is no chance to get internal humidity much below this, except when the dehumidifier is running.

 

[Penners]

Heavy breathing can increase RH.

 

[Matt Green]

Heavy breathing can increase RH.

Penners: keep a dehumidifier next to the phone.
Joce: listen for whirring in the background if those calls start again

 

[MdB]

:shock:

 

[JoceAndChris]

:lol: :lol: :lol:
Nice one Matt!

 

[Penners]

Penners: keep a dehumidifier next to the phone.

You have a very dry wit, Matt.

 

[columbus]

Thank you so much. I've been working away for a few days and have come back to find all this incredibly helpful advice, which has given me a lot of ideas.

I'm going ask another dopey question here - how can I improve the ventilation and keep the cellar warm at the same time. If I open the cellar door and window to increase the air flow, that seems to make it drier but also definitely colder.

I'm going to give a test are of the cellar floor with the old wire wool and wire brush. If I do a few a bricks a day I'll probably manage the whole floor before I get too old to get down the cellar stairs. It's not huge but it does seem to take ages.

Columbus

 

[johnandrew]

Penners: keep a dehumidifier next to the phone.

You have a very dry wit, Matt.

Very droll, penners.

 

[middi]

Thank you so much. I've been working away for a few days and have come back to find all this incredibly helpful advice, which has given me a lot of ideas.

I'm going ask another dopey question here - how can I improve the ventilation and keep the cellar warm at the same time. If I open the cellar door and window to increase the air flow, that seems to make it drier but also definitely colder.


Columbus

I am afraid it is a bit like teaching a donkey to become race horse, you may end up with a very clever donkey but never a race horse. Cellars were built to be cold and well ventilated.
To modify a cellar to become living accomodation it would require proper evaluation of type of ventilation and heat required whilst at the same time eradicating any natural damp that cellars are prone to.

Middi