Blown Engineer bricks

[lawrenso]

Hi All,

We have an outside wall - part retaining as house is lower than the road, and it is topped off with red engineering brick - ie smooth and slightly glazed - laid on their side. They are not solid. Our neighbour has the same.

I noticed the other day a large number of these bricks have blown their faces. The house is only coming upto 6 years old and although the weather has been bad recently I would have thought that modern bricks should have had greater resistance and last a lot longer than this. our neighbours are the same and one of their bricks has basically shattered through the whole of the body.

To be honest, I always thought the cement on the wall was very soft and sandy and they suffer terribly with moss which when you pull it off pulls chunks of very red cement out with it - could this be the cause of it?

Also a bit concerned that we have the same bricks in another wall where only a couple of bricks have blown although this is a full retaining wall between our neighbour and ours (about 3.5" high) - again as caps and also suffers moss. Only the odd one of these is blown

Any advice/thoughts greatly appreciated

Regards

L

 

[Blagard]

The bricks used don't seem up to the job, engineering or not and there are facing bricks that look them too!

A better choice would be a replacement engineering brick - hopefully not defective ones bedded in a stronger mix.

I would not expect the soft mortar to be the problem, but it does seem excessively weak and hence when replacing the bricks go for something stronger.

 

[lawrenso]

there are facing bricks that look them too!

Hi Blagard,

can't get my head round the bit above - could you clarify please.

Would the mortor in the rest of the wall be an issue with it being soft as it is retaining?

Cheers

L

 

[Blagard]

True engineering bricks are stronger than most facing bricks. They do not easily get saturated. The Red Engineering Bricks frequently used in manhole construction are similar to what you have described. But I don't think that is what they are, or if so, they may be defective.

There are also ordinary bricks that look the same but are not an engineering brick and will absorb water more so than the engineering brick. If such a brick was used a coping (on top of the wall), it could easily "Blow" from Frost damage.

It is common for boundary walls to have facing bricks in the general area of the wall and then be capped off using an engineering brick.

It's a rum business because even some facing bricks can be as good and strong as engineering ones. That should not bother you because the fact the bricks are perishing suggests to me they are simply not up to the job and either defective engineering bricks or a facing brick that is unsuitable.

If the bricks in the wall below are not perishing then that's absolutely fine, don't worry about them.

Don't worry about the mortar either - a soft mortar in facing bricks is not unusal (The nature of the retaining wall behind what you can see may be completely different, and unless you know otherwise should not be a concern.)

All red bricks may look the same but believe me they are not!

 

[Blagard]

Drat the Website is getting a bit flaky! - Duplicate!

 

[Nige F]

Exellent answer But to add...Red Coloured Cement in a retaining wall and spalling bricks after 6 years .. Deja Vu for me on an estate of Housing Association properties in `86 built 1980.... The coloured cement is not right - well, it wasn`t then and the lot had to be taken down and rebuilt . ( taxpayers expense) You need to get expert advice with someone on site to look

 

[Blagard]

Exellent answer But to add...Red Coloured Cement in a retaining wall and spalling bricks after 6 years .. Deja Vu for me on an estate of Housing Association properties in `86 built 1980.... The coloured cement is not right - well, it wasn`t then and the lot had to be taken down and rebuilt . ( taxpayers expense) You need to get expert advice with someone on site to look

Colour addatives to mortar are not a problem these days. They have been around and OK to use for a considerable time. The spalling is on the top course. I think you are thinking of retaining walls that can and have been built entirely of brickwork. - Actually never done one like that myself the ones I have been involved with had either a Blockwork or Concrete structure to ground level on the high side. then facings in front and on top. Had the general area of brickwork also been spalling then I would have suspected an all brick construction that also had no membrane/RIW to the rear. Six years is a decent time to establish the wall has generally been built OK with no foundation or other structural problems.

By all means have some-one look at it if really worried - However, I think that would be over the top for dealing with perishing bricks on the top course.

I'm not sure if you can get them for recent builds, but I managed to get the Building Control drawings for my own 1937 house from the Records Office. I did have to do the search myself before calling them up and ran off copies for all the neighbours at the same time as a general interest thing! - I did this as a member of the public.

One of the first projects I was on for a housing development trust was on a Plymouth hillside. That project had exceptionally big retaining walls around 4m high. I'm pleased to think they didn't have to pull those down

 

[noseall]

Coloured readymix batched mortar is pants.

.......but flexible.

 

[Chukka63]

i think class B engineering bricks are crap,they dont do what they say they do on the tin.ive seen loads of class B eng bricks flaking/failing.i think some of the semi engineering bricks,blagard was referring to hold up as well if not better.only real option for these types of wall IMO are class A but a bastard to lay compared to any other due to taking so long to "sett" before pointing and "weatherproof",by which i mean rain attack or frost.

 

[lawrenso]

thanks for all the replies guys

When I said red - this is when wet - what I gather is the high sand content??

Cheers

Steve