Jerry's renovation blog

[facthunter]

Summer's THERE, not HERE. .  Nev

[Jerry_Atrick]

OK - back to the damp issues on the outside of the house..

 

On the back wall of the house, we have had some render which has literally been peeing away over the years, exposing the stone hehind it. In my mind, I would like to take the render off, re-point/mortar teh stone wall and be done with it.

 

The builder said the reason why it was peeling off is that it ia cement based render, which doesn't allow adequate breathing. So we took him to the front of the house and - yep - according to this fella the render on the front of the house is cement-based rather than lime based and that is the most likely culprit - apparently he has been doing a lot of these damp-fixes lately.

 

Our house is a grade 2 listed house. The reason why the front of the house has (new; < 6 year old) cement render is that a big old tree fell on half the house before we bought it and the builders the insurers used decided to use cement render. What peeves me off is that our house is listed, and we can't put anyting on the outside without the listed building officer approving the material which has to be consistent with the original materials as muchn as possible (actually we have to reclaim as much of the original materials as we can). Yet, for some reason, the then listed building officer signed off so much crap, including a bay that doesn't even meet regs, not has any consistent with original material in it. The whole listed building system here is a joke and it is enturely up to the discretion of the listed building officer.

 

So, waiting for the quote to come in, but as this bloke has been used by about 5 households in the village and comes with a good reputation, he would have to be putting in a wild quote to come close to losing the job.

Still waiting for he opther half ot he roof to start!

 

 

[facthunter]

That's one of the problems with older Countries. Too many old sewers, sloping floors ,Old bricks and Dog $#!t. Oh and silly rules and quaint customs.  Nev

[old man emu]

I carried out a survey this week of a little brick cottage that we built in 1916. The building inspector who did the pre-sale report said that there was rising damp damaged to one wall. I would have thought that if an empty, closed-up house had rising damp, the smell should have knocked me over as soon as I opened the front door. But it didn't. I strongly suspect some damage to the wall, but at the moment the interior of the wall is sheeted with fibro cement. I'm going to tell the owner (a mate of mine) to carefully remove the fibro to expose the wall. I also fear that the wall has started to lean outwards from the top. It has only moved about 3/4 of an inch, so maybe it can be pulled back into position.

 

I was taken aback by the quality of the wood used in the internal doors and sash windows. Beautiful stuff!. Unfortunately the interior has been painted in very dark reds and greens, and I'm not sure idf the ceilings are painted yellow or incredibly stained by tobacco smoke. 

 

It's a beaut little house which he got for about 50% of the median house price in the town. I'll post some pictures when I get around to downloading them as I only got back home late this afternoon from seeing the kids in Sydney and Canberra.

[facthunter]

The rising damp is caused by salt accumulation and that would stop microbial infection.    Nev

[old man emu]

Actually, there was condensation on the window pane of the room where I think there is damage.  Just looking at the site on Google Maps, the building is in Goulburn and aligned sort of NNE, and the wall that shows the most weathering is the SSE-facing one. I wonder if the weather damage is done during summer. The wind is most often from the east for 3.4 months, from 25 December to 8 April, with a peak percentage of 41% on 1 January. The most rain in Goulburn is February, with an average rainfall of 62 millimetres.

[willedoo]

7 hours ago, facthunter said:

The rising damp is caused by salt accumulation

I thought it was more the case that salt accumulation is caused by rising damp, not the other way round. Rising damp is water seeping upward into the building by capillary action, bringing soil salts with it in the process. As the moisture in the building evaporates it leaves the salt to accumulate. The accumulated salt crystals in the masonry can gradually grow and damage it, which is why rising damp in saltier soil areas will damage masonry walls more than it does in areas with less salty soils. On the other side of the coin, salt prevents dry rot in timber, as dry rot bacteria needs timber, humidity and fresh water. I've heard of timber boat owners putting rock salt in the bilges to protect from dry rot.

[facthunter]

Osmosis is what causes the water to rise in response to the high concentration of salts. The moisture flows to even the concentration. That's how osmosis works. Salt kills bacteria and fungus and moulds also by osmosis (sucks the moisture out of them). Ie salted meat. Honey/sugar works in the same way  Nev

Edited July 31, 2023 by facthunter
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[old man emu]

I have a question about brick walls that is not related to rising damp. 

 

Does painting a brick wall encourage deterioration by preventing the brick to "breathe"?

 

The house on the left is the one my mate just bought.

 

These three pictures are of the side wall which does not get direct sunlight, and has been painted.

TOP:   MIDDLE:  BOTTOM: 

In the photo of the bottom of the wall, the base is along the left hand edge of the photo.

 

Do you think that the best idea would be to strip the paint off to expose the bare brick?

 

 

[facthunter]

I'd say the foundations' are  moving. Paint removal won't make any difference.   IF they are wet and freeze that's another matter as ice expands but the damage would be the outer surface chipping out.   Nev

[old man emu]

6 minutes ago, facthunter said:

the foundations' are  moving

I'm not worrying about that. The cracks on the other side of the house are worse. 

 

Since Goulburn does experience freezing temperatures and wet weather, I wonder if painting the wall with a waterproof seal would be worth the cost. Afterall, the wall has been standing for over 100 years now, and the outer surfaces of the bricks are in good nick.

[facthunter]

I've done that to solid brick walls just to stop water leaking through. Nonporite and Ducksback come to mind Fix any leaking downpipes and get that water to the street gutters if possible When a continuous crack is wider at the top, you can guarantee the foundations are broken. There may be buckshot gravel or something  underneath  there.   Nev

[willedoo]

7 hours ago, facthunter said:

Osmosis is what causes the water to rise in response to the high concentration of salts. The moisture flows to even the concentration. That's how osmosis works. Salt kills bacteria and fungus and moulds also by osmosis (sucks the moisture out of them). Ie salted meat. Honey/sugar works in the same way  Nev

Nev, I still think you're getting it back to front about salt being the cause of rising damp. If you don't have an impermeable barrier, water will move upward from the soil by capillary action. For example, fresh water (with no salt concentration) will still wick. Plants draw moisture from the soil and transpire by capillary action without salt being the cause. The only way I can see salt as the cause of rising damp would be if the water penetrates because of the natural amount of salt in the bricks (from the clay used to make them). Here's a S.A government guide on salt attack and rising damp that explains a few things.

 

https://cdn.environment.sa.gov.au/environment/docs/saltdamp_techguide.pdf

 

 

Edited August 1, 2023 by willedoo

[facthunter]

There IS capillary action but osmosis is the way plants get their water up to the Leaves. . Keep looking and you shall find.. It's NOT just SALT that works. Anything that dissolves in the solvent which in this case is water.

  ' Hey that reference is pretty comprehensive and worrisome. Put you OFF masonry and brick walls forever and salty areas.  Nev

[willedoo]

The point I'm making Nev, is that salt accumulation is a by product of rising damp, not the cause, as you previously said. If you can provide some links to technical info that backs you up on that statement that rising damp is caused by salt accumulation, I'll gladly admit I'm wrong and will have learned something. However, I've checked out any info sources I can find and none of them say rising damp is caused by salt accumulation. They are all fairly consistent in saying rising damp occurs because capillary action causes the moisture to enter the building and may or may not bring ground salts with it in the process. You can get rising damp with soils of a high salt content or those with minimal salt content. Take the salt out of the equation and you can still get rising damp. Other factors might cause the ground to accumulate salt, but rising damp into the building is not caused by the salt in the ground. The rising damp brings salt present in the soil with it and the evaporation leaves the salt there in the walls.

[facthunter]

The Fullsome article you posted sees salt removal as a cure IF there IS a cure. It all seems pretty bad in salty areas in particular, which SA has plenty of.   Nev

[old man emu]

Thanks Wlliedoo! The answer to my question is given in Chapter 5 of https://cdn.environment.sa.gov.au/environment/docs/saltdamp_techguide.pdf

 

When a wall warms up after a cool night, the air contained within its pores expands as it warms and a small proportion moves out of the wall via the connected pores. As the wall cools down again the air within contracts and air moves back into the wall from the atmosphere. And so masonry walls ‘breathe’ – out as they warm and in as they cool. 

 

Anything that prevents a masonry wall breathing will reduce its life expectancy. Coatings that are designed to seal the surface of masonry walls (and so ‘protect’ them) risk trapping moisture behind the coating and causing a damp problem elsewhere, such as on the other side of the wall. 

 

So my advice to my mate will be to scrape all the paint off the outside of the bricks.

 

[willedoo]

5 hours ago, facthunter said:

The Fullsome article you posted sees salt removal as a cure IF there IS a cure. It all seems pretty bad in salty areas in particular, which SA has plenty of.   Nev

I was wondering why there was so much reference to South Australia in online information on the subject. I'm not very familiar with the bottom half of S.A., only from the Flinders Ranges north. Plenty of salty lakes.

[facthunter]

There's a lot of stone used and a lot of salt. That article would be a lot of help to a lot of people  in SA but It would turn me Off using stone or brick.  Nev

[old man emu]

3 minutes ago, facthunter said:

It would turn me Off using stone or brick

Someone here recently said that Australian houses are built to last only 40 - 50 years. That might be true of the timber-framed hose with its veneer of wither brick or fibre-cement sheeting. But look at the buildings we have that are now approaching 200 years old - and look at the even older buildings in England and Europe. Bricks and stones, my friends, bricks and stones.

[willedoo]

2 hours ago, old man emu said:

Anything that prevents a masonry wall breathing will reduce its life expectancy. Coatings that are designed to seal the surface of masonry walls (and so ‘protect’ them) risk trapping moisture behind the coating and causing a damp problem elsewhere, such as on the other side of the wall. 

 

So my advice to my mate will be to scrape all the paint off the outside of the bricks.

Going by that advice, I would think a limewashed brick wall would breathe much better than one painted with acrylic paint. I like whitewash in the right application. It only takes two or three years to look 100 years old.

 

1 minute ago, facthunter said:

There's a lot of stone used and a lot of salt. That article would be a lot of help to a lot of people  in SA but It would turn me Off using stone or brick.  Nev

Modern cavity brick or brick veneer construction is not too bad with adequate damp coursing and good clean weep holes, but stone is a whole set of problems. Stone looks nice is about all I can say for it. I doubt anyone would build old fashioned 9" solid brick walls anymore; that's most of the problem with damp in the U.K. buildings and our older ones. Maybe ok as an internal feature wall to have the English bond or Flemish bond look.

[onetrack]

I live in a house that's 66 years old, and built with cavity-type double clay brick using lime mortar, on limestone foundations, with the front of the house rendered and painted.

I don't have any problem as regards rising damp, but I would have to opine that's because the local soil is sandy and well drained, and the timber floors of the house are on stumps about a foot high, with wall ventilation just above ground level all round.

 

Most houses that suffer from rising damp have poor foundations, poor drainage, and are sited on heavy clays, where groundwater doesn't drain away adequately.

 

I have no doubt this house is capable of lasting 200 years or more - but a large number of houses similar to mine have already been demolished because of increasing density, and a need for new owners to have the latest and greatest in 2-story buildings, with all the new "energy-efficiency" ideas, and legislated conditions applied to new builds.

 

But from what I see of new builds, with fast-wall brick and many other el-cheapo building ideas and products, I'd have to opine that they'll all be gone in 50 years. I'm amazed at the number of new homes being built with lightweight steel studwall construction, clad with some pretty crappy cladding materials.

 

Edited August 2, 2023 by onetrack

[willedoo]

With the modern walls eg: brick veneer and cavity brick, the only thing stopping the brick walls falling over is the flimsy metal wall ties. Cavity brick is the most vulnerable in salt air coastal areas as the wall ties are only round gal wire, and not hot dipped gal either. I talked to some brickies who had gone down to work on the 1989 Newcastle earthquake reconstruction, and they said brick veneer walls were still standing, while a lot of cavity brick walls fell over because the wall ties were rusted through. When building them, at the end of every day, the brickies clean the cavity by scraping off excess mortar and hosing the cavity out. But the problem is that mortar collects on the wall ties during the day and the lime reacts with the metal ties and degrades the gal coating.

 

The same thing happens with veneer ties, but they have a lot more metal to rust away, whereas the cavity ties are basically round wire.

[willedoo]

This is a Fremantle heritage building advice sheet; fairly easy reading.

 

https://www.fremantle.wa.gov.au/sites/default/files/Technical Advice Sheet -5 Dealing with dampness in old walls.pdf

 

I remember the first time I went to Perth, my nephew who lived in Rockingham took me for a drive around the centre area of Fremantle. I was amazed at the number of heritage buildings there; it was like stepping back in time. If that was Queensland, old Joh would have sooled the Deen brothers on to them long ago.

[willedoo]

The old style solid brick wall construction of double brick, alternating stretcher and header courses, is why bricks are the dimension they are today. Standard brick size is 230 mm long and 110 mm wide, so twice as long as they are wide when you allow for a 10 mm mortar joint between the headers. 110+110+10=230.

 

The introduction of metric measurement was a huge gift to the building industry. The main variation in bricks is the height. The gauge is the laid height, so a standard 10 mm bed joint with a 75 mm height brick is 85 gauge. But a standard 10 mm bed joint might not work out given the thickness of the batch of bricks and the height from base to roof eaves. With metrics, it's easy to figure out with a calculator. In the case of 75 mm thick bricks and a base to eave height of 2400 mm, 86 gauge is 27.9 courses. 85 gauge is 28.2 courses. Both of those work for 28 courses. One you pick up a little bit, the other you squeeze down a little bit over several courses to neatly fit 28 courses in. Compare that to figuring out the same thing if the gauge is 3 and 3/4 inches. Trying to divide inches and parts of inches into feet is something that brickies don't miss having to do.