Garden wall wet damaged bricks

[Justin]

My back garden is about 2ft higher than the neighbour's, a retaining wall divides the two. The bottom courses are blue brick, the upper courses are a rather sandy decorative brick. I've just found out that part of the bottom course of decoratives are severely damaged on my neighbours side and need replacing. This is because my garden slopes slightly from left to right putting these bricks below ground level on my side, causing them to be wet and spall on the open (neighbours) side. I also now know that I own this wall outright (;-

[adder1969]

[Phil L]

The general idea is to remove about 4 bricks at a time and replace 3, do this in a few sections, then the following day, do the sections you missed, this metod can also be used to install a plastic DPC in a house wall, if anyone is interested, obviously the DPC goes in in pieces and is overlapped....you don't need a DPC in your wall BTW!

If it's taken 30 years for them to get so bad that they need replacing, just use normal bricks, either you or your neighbour will probably be dead before they need doing again.

Why not just use blues? - nothing you put on it will prevent spalling, normal water penetration isn't a problem, it's the frost that causes spalling and you can't stop either with chemicals because the water is ever present and goes in through the part of the brick you can't see.

Even iof you buy the exact same ones, they won't match

[Justin]

Sorry I didn't make it clear that this wall is about 4ft 6 high on my side,

7ft high from the lower ground level thus retaining about 2ft 6 of soil. I wouldn't want this to come down during the work!. I'd thought of doing it in sections, though given the poor state of the bricks no more than 2-3 at a time. I really want to take two out first (AB), put in (A) then take out (C) then put in (B) etc all along the line. This seems easier as it's much easier to drill out & replace bricks if they are not completely enclosed. Hence quick-set mortar plea for help - is such stuff viable and available?.

Yes obviously this wall doesn't need a DPC. I was thinking if the suspect bricks had DPC chemicals injected, well into the depth of the brick (middle or even further back), this might stop water penetrating the brick from the back to the front and might check the spalling. But it was just a thought.

Because water is coming from the back, rendering the brick faces will have the reverse of the desired effect of keeping water away from the brick, and would the render be a violation of my neighbours territorial airspace?.

Justin.

[Phil L]

No, and if there is, it doesn't work...if you do it this way, it's akin to taking the whole course out at once because there will be no strength left in the base of the wall until it all sets, hence my reccomendation to take out 3 or 4 and replace 2 or 3, leaving one out for a start the following day.

Not unless he's a solicitor :-p

Rendering the bottom few feet may be the easiest and simplest solution, yes you are trapping water inside the bricks, but you are protecting the bricks and the water from frost...if you decide to do this, give the wall a few coats of PVA before rendering, and remove any loose brick or mortar material, use a 3:1 sand /cement mix and give it two coats...you can paint it with masonry paint after it's dried to give it a more acceptable finish.

[Justin]

The logic of the original idea was...

1) Is there such a thing as quick setting mortar?. I've got quite a length to drill out & replace, the idea is to have the mortar set almost as quick as I can go along the wall.(so the wall won't fall down!).

.. but you may well be right about quick-set mortar not being a viable thing.

Justin.

[Phil L]

Only in cartoons I'm afraid.

[The Natural Philosopher]

leave a few gaps in it next time for water to drain out.

[fred]

I've a bag of Supamix quick setting cement here, "Set & serviceable in 30 minutes", any reason that won't do for mortar? Trouble is it's only a 1kg bag and from memory 3quid for that but I'm sure there will be bigger (more cost effective) bags available. Bought from Buy&Q.

[Andy]

Yes there is such a thing as quick-setting cement. It contains chromates and other interesting stuff. It does what it says on the bag. You have to work quickly with it so don't mix up a lot in one go. Conventional mortar is workable for maybe two hours, the quick set stuff goes unworkable in minutes. I know 'cos I've used it. The sheds stock it.

Andy.

[bilbo*baggins]

Justin,

You cannot afford to leave it alone. The wall is your property, and your responsibility. If it collapses on someone, you *will* have an amost indefensible 'public liability' case against you. And your household insurer is unlikely to be helpful, as they almost certainly have a clause requiring you to keep everything structural in good order and condition. The wall isn't, and you clearly know it.

Can you not get a reliable tradesman - with public liability insurance

- in to do the job? Then you have demonstrably taken 'reasonable care' to have the wall made good - and safe. And you have a come-back if anything goes wrong.

Bilbo

[meow2222]

Another way to quick set cement is to mix mortar up using boiled water. Trouble is is sets very quickly... :) Seriously, the issue is that although the initial set may be quick, the following 28 day hardening period is no faster. So since its a retaining wall, I'd do some of it, leave it a month then do the rest.

Wood props can be used as temporary support, as long as theyre solid enough, jointed strongly enough, and footed firmly enough.

Painting the back of the new bricks with bitumen paint will reduce water flow into the wall. Bitumen is not the same thing as injected dpc chemicals, which would not stop water ingress under pressure.

If present bricks have spalled, I would not want to replace them with the same type, as they're likely to go the same way.

If the bricks only have damaged faces, lime rendering them would give them a sacrificial layer, and should stop further deterioration. The lime lets the water come out, but the lime takes the freeze damage, thus not affecting the structure of the wall.

NT

[Tony Williams]

[Justin]

I'm not quite sure if mortar made with QS cement or hot water would it give a sufficiently strong bond to the brick as the short-life wet mix doesn't have much time to soak in?... If this is OK the only problem would be having to wait 28 days for each section as suggested.

Justin

[adder1969]

It's not uncommon for a DPC to be put between the wall and the supported earth and that would probably have saved the bricks from spalling.

How many do you have to replace?

[Phil L]

You can wait 48 hours for each section, it takes 28 days to reach it's full strength but is perfectly set enough for a garden wall in 2.

[The Natural Philosopher]

Agreed. In warmn weather, overnight, in cold, a couple of days.

[Justin]

...In the sense that a DPC course is a horizontal defence against rising damp

A impervious layer between the bricks and the earth certainly would have helped.

About 20 to 50, depending on what happend in the lesser-damaged cases.

Justin.