We have just bought a victorian terrace and have a clear problem with damp at the bottom of the walls - (rising damp?) We are against the idea of injecting silicon and want to try all other angles first.
My understanding is that we need to identify any possible drainage problems which may be introducing damp, sort out the seventies windows without trays, and also to clear the cavities to ensure the dampcourse is not bridged.
So to the question! How do I approach the clearing of the cavities? Is it easier from inside or outside? Do I take a brick out above the dampcourse? How far apart should I remove bricks - is it the distance I can reach?! And do I need to replace the prevous brick and wait for the mortar to dry before I do the next one? All help on dealing with damp without recourse to chemicals very gratefully received.
Hugh

Don't discount the possibility that it could also be condensation.

As Nick says we need more information.

Forgot to say, easiest way to establish a cavity, or not, is to measure bthrough a window or door opening. If it's about 10", then it's a 9" solid wall with plaster. If it's about 12", then you have a cavity. You can also look and see if you can see any headers (apparent half-bricks) which will be tying the (9" solid) wall together. However if you haven't got headers, you still might not have a cavity. I have a Victorian hse with wall ties but no cavity. The measure-thro-the-opening test is the clincher.

Nick

PS: Got high yard levels or flower beds?

As noted above, it was exceptionally rare for Victorian Terraces to be built with cavities, particularly in the South of England. If you are unfortunate enough have a Victorian house with cavities, rising damp msay prove to be the least of your problems.

Rising damp is exceptionally rare and caused by a hydraulic action within the capilliaries of the mortar.

Confirming a few of the points above:

Check your external gutters & pipes, to ensure that water is not being directed onto the wall. Next check that the wall itself is not damaged. Then check that there is no internal source for the water (leaking pipe etc). After that check the levels of the ground to ensure that it is lower (preferably by more than 6") than the wall (not always a problem this one). If you have hardstandings outside, check that they fall away rather than towards the building. Then check drainage to ensure that it is taking the water away. lastly, dig a small hole adjacent to the wall to see what the water levels are: If they are high permanently, then think about installing additional drainage.

Once you know the source of the water, finding a solution is usually easy.

Thanks for the many replies which make interesting reading. I have lived and worked in many victorian houses which have always had cavities, maybe just the areas that I have lived. I have just been round to the house and the walls definitely have a cavity of around 4 inches. The main problem I know of is two large windows that were added in the seventies which are rotten on the inside at the top and have no cavity trays, these we are going to replace with trays. The clearing of the cavities I assumed was an important job but I am interested that Tony says dont remove bricks, why and if the cavity is blocked surely this will cause damp inside? I was also interested by jons reply that dampness could be the least of my problems, do I want to know what he means?!! The plaster in the house is original and sound generally and obviouslly lime based. I plan to line the walls with lining paper and starch paste and paint with clay paints.
My second thread which is kind of related is cavity wall insulation, experience tells me that it is bad having had damp problems in my present house, has the technology moved on and are the energy benefits worth the damp. I very much appreciate peoples opinions.
Hugh

>>I have lived and worked in many victorian houses which have always had cavities, maybe just the areas that I have lived<<

9" solid was the norm in Victorian times. The very first cavity walls built by the Victorians used cast ties between the bed joints. 1890 would be the right period for this. For Victorian buildings, particularly with damp, the ties will almost certainly by now have been rusted away or may just be there in nominal form. Thus, unless it were constructed as a diaphragm wall (not common) the outer leaf of the wall could now be effectively freestanding and only held up by the window frames. Once separation starts, the eccentricities of the build very slowly start to gradually deform the outer skin away or towards the inner skin.

With luck the wall will stay where it is. The majority do. However, when movement starts to occur there is little economically that one can do about it other than to remove the outer skin, drill and fix new ties then rebuild the outside. The ones that I have advised on generally end up being demolished. If caught early, it is possible to stabilise the outer skins by drilling and fixing through but this is unsightly.

If, on the other hand you have a Victorian example fo a diaphragm wall (similar to a cavity but with the 'ties' being built using brickwork), it will be a little colder than a full Victorian example of a Cavity but warmer than a 9" soild. Plus it will have a significantly higner lifespan.

Edit: Another thought: some types of insulation, foam infill injection, can act a a tie particulaly if on dry internal surfaces. However, if they debond thay can, under some circumstances, make the problem worse rather than better. They are also likely to accelerate the deterioration of any existing ties that remain.

Good luck!

Hi Nick

Yes, ties built in walls in well heated houses not subject to air or moisture can last a very very long time. If one allows moisture to get in, the lamination process that occurs can cause significant problems with the wall (as the stresses induced by lamination are high).

It will be interesting to see the impact of future legislation on your type of house: For instance, one study, using median figures for improvement of housing stock, believes that existing building stock will need to be upgraded from an average energy rating of E to that of an A. It is difficult to see how this can be done easily without external cladding, but, on terraces and other buildings with sensitive facades, this may be impossible from a planning point of view. Thus the answer may be some form of internal addition. However, this will create conditions in the external skin that will vastly accelerate the deterioration process of walls with potential lamination problems. Hope this not too negative but thought worth mentioning.

Hi Hugh. Yes, the aswer may have been no ;-)

There's a number of proprietary products but drilling and fixing through is generally the method: Brickwork needs to be sound: Can be unsightly and a tad expensive as needs to be stainless steel and onbviously labour costs are high. Unfortunately the cheaper product methods also have no central drip but if you're filling with insulation by injection may be of no concern.

Good luck !

It is possible to do the entire job without using wall ties providing you can accept a slightly thicker wall and intermittent external skin stiffeners either facing out (or into a widened cavity)

But it's a little more difficult in practice than I'm making it sound

Terry. Rendered panels are relatively common on new developments in the UK.

Posted By: jonexisting building stock will need to be upgraded from an average energy rating of E to that of an A. It is difficult to see how this can be done easily without external cladding

Insulation isn't the be-all and end-all. Massiveness can be quite a good, or even an excellent, alternative to U-value, depending - needs to be understood/modeled. Empty unfilled cavities then become a great asset - valuable for future methods, whereas cavities filled with today's puny gunk will be a real future faff. Fill then with something massive - subject as I say to understanding/modeling. 75mm of hempcrete sprayed onto the interior surface is the only conceiveable way of internal insulation - because it's not lightweight like insulated plasterboard - it's moderately massive, keeps the wall mass connected to the interior, and has other magical properties.

Massiveness does not help with insulation. Try living in a cave. All it does is to integrate the temperature differential over some time period. Now if you add internal insulation, with massiveness outside it, it is good, but on its own its a PITA, its the air around you that keeps you comfortable, not the internal temperature of some wall or floor.
Frank

Terry

Having done many buildings with these I've never actually seen one of them fixed! However I haven't seen any mechanical fixings used during visits post the process

Tom

Understand where you are coming from. Then there are building regulations and CfSH which are based on the idea that insulation is the be-all and end-all

The way the CfSH is currently phrased it would appear that the 0,8 U figure will be almost mandatory. I understand why they are doing it (lowest common denominator and all) but it seems to me that it will be a lot of work to do otherwise