Solid brick walls

[Jeweller]

I'm hoping there's a specialist around here who can help me with advice about our walls.

It's an old house built of brick with no cavity. The oldest bit (C1720) has solid walls 3 bricks deep and mostly these are OK. A later addition (C1840) has walls only 2 bricks deep and it's these walls that are causing us some grief.

The outside is painted, (the bricks are too soft for sand-blasting) and the pointing is apparently intact but I'm happy to be advised on this. The wet summer has brought damp patches inside these 2 brick deep walls. I am loathe to try and seal the walls either outside or inside, the seal only breaks down sooner or later. I feel sure there must be a way that the insides were prepared/treated that could cope with damp weather conditions when these walls were originally built.

We do keep a trickle vent open in the windows and the rooms do get heated when we have the central heating on. It's not a permanent affliction, there's precious little damp in normal weather conditions.

Any more information needed? Cheers D

[meow2222]

Classic stuff, this happens to lots of properties, and is usually caused by incorrect maintenance. Part of the solution is removal of the paint - certainly not by sandblasting thugh!

This explains more...

[Jeweller]

Thanks for that thread, it touches all the points I needed.

[Tim Lamb]

In message , Jeweller writes

Are you sure it is penetrating damp rather than condensation on a cold surface?

A flat we let had just such a problem on a North facing uninsulated cavity wall. It is likely our tenants are not allowing sufficient heat/ventilation into the room during a wet, coldish Spring.

regards

[Phil L]

Under normal conditions they would stay dry naturally - it's only the paint that is causing the damp

The facts appear to be:

1) This wall gets some severe weather, and over the years, the brickwork has been badly affected, probably by rain / frost cycles. 2) Some braindead clown has painted the walls in the past, in an effort to hide some of the badly affected parts, instead of cutting them out and replacing some of the bricks as was required. 3) You are now lumbered with a damaged wall which is getting steadilly worse and will continue to do so until it is completely overhauled, because the paint traps moisture in the brickwork.

You now have several choices:

1) Patch up and repaint - 'make do and mend', which is only a temporary measure, which is what has already occured, maybe several times 2) Completely overhaul the entire wall, which means complete removal of all of the paint by fair means or foul, IE sandblast the whole thing, then cut out and replace any damaged bricks, and finally repoint the whole thing.

[meow2222]

Mostly good advice, but

that would be all the bricks, after you've sandblasted them. They're soft 1800s bricks. Theres a water vortex thing that does the job, but I dont recall the name.

When it comes to PP stuff it really is best to ask at that other place.

NT

[Anna Kettle]

A couple of names Joss and Doff spring to mind. Is that the sort of thing you mean? I've never used them or even seen them used mind you

Anna

-- Anna Kettle Lime plaster repair and conservation Freehand modelling in lime: overmantels, pargeting etc Tel:    (+44)  01359 230642 Mob:  (+44)  07976 649862 Please look at my website for examples of my work at:

 

[mail]

Dear D There is one more possibility that has not been discussed and that is the presence of hygroscopic salts in the internal plaster due to past water penetration bringing them in. To test for this check on the damp patches with a damp meter and see if they correlate not to the rain (ie lateral penetration) but to the relative humidity which can be high with no rain. I understand that the patches come and go with the weather (rain) so you need to determine this. If it is hygroscopicity your cure is to identify the locations (use a pencil) over time - add a small margin for a factor of safety (say 150 mm but use commonsense) - and remove all such defective plaster and repair with a similar plaster to the original. If it is lime then use lime putty in tubs not bagged lime and mix up the mortar in a tub and leave it for as long as you reasonably can (coars stuff) say 6 months before using it. check for the presence of any hair acting as binder and incorporate if you need to .

I was confused as to how thick the walls are. Three bricks deep is massive and I would be suprised if you are getting penetration through

27" of brick. Are you sure that you do not mean 1.5 bricks (13.5")and one brick (9") respectively? That is much more likely in the sort of building you are describling.

When I was faced with exactly the same problem as you on soft red rubbers which had been painted over by my previous owner so the outer part of the brick had absorbed some of the paint and there were pockets therein painted -I considered lots of options and tried samples of all sorts of cleaners chemically and manually. None worked and in the end I had no choice but to get to it with a dirty great angle grinder with a face disc on it and took off the guard so I could VERY carefully take off the outer 1mm or less of the brick. I was told this would ruin the "face" of the brick and it would all degrade in a few years. I could see no logic in this statement as the material of the brick was not different on the face and 05 or 1.0 mm in. After removal of the paint I hand rubbed each brick with sand paper (orbital and hand sander) to remove disc marks and then repointed it with tuck pointing using red brick dust as my sand for the back of the tuck. I did the work some 25 plus years ago and it looks as good now as it did then. I endorse the other views on avoiding sandblasting and from my own experience would urge you (unless you wish to risk getting extensive dry rot in a couple of yeas) to avoid any high pressure water based methods. Good luck

Chris

[stuart noble]

Option 1 can be more than temporary if you use a solvent based masonry paint such as Johnstone's Storm Guard. I hate painted bricks as much as anyone but option 2 may not be feasible for most people. Paint doesn't hold water behind it if it's well bonded to the substrate and produces a rain proof seal. The problem is that water based masonry paint don't do this.

[stuart noble]

The other place is simply you spouting stuff you can't get away with on here.

[The Natural Philosopher]

Or rising damp due to Zero DPC and sodden ground, and boy has it been sodden this year..

If uyour damp p[atches are all low down, - usually less than 4-5" off the floor, that might be it.

If they are all high up, suspect guttering failure etc.

If it is penetrating, and you cant get the paint off, then put more on to stop the water getting in.

As I repeat endlessly, there are two approaches to dry houses: stop the moisture getting in, or help it get out easily.

Bad paint doesn't do the former, and prevents the latter ;-)

[stuart noble]

I've never understood that either and my experience is the same as yours.

[Andrew Gabriel]

A couple of observations...

There are some bricks which have a different facing layer. My parent's house it built with just such. I don't think they are very common though.

The surface of some bricks can have an enhanced protection against moisture due to the way they're fired. This came up on my bricklaying course where we were warned not to use the top or bottoms of bricks as weather-facing surfaces unless you are sure the bricks were designed for this. These surfaces do not in general have the enhanced protection against moisture due to the way bricks are stacked in the kiln. I guess you may get the same if you remove the outer surface of such bricks.

[meow2222]

Thank you Anna...

[meow2222]

for anyone reading if you ask there about whats discussed they can point you to expert reports, SPAB etc. Its Stuart that cant be botherd to get himself informed.

NT

[mail]

Thanks Andrew That explains it! Someone advising generally when it is only applicable to the specific. Chris G

[meow2222]

IME old bricks are generally that way. Once the outer harder denser fireskin has gone, gradual freeze thaw disintegration is likely. You've only got to look round Victorian housing areas to see this occurring.

NT