Brickwork mortar 1:11 cement to sand mix?

[outmyway]

I'm in a new build Bellway house,

The mortar up to the first lift is very crumbly.

I've had it tested and lab report was a 1:11 cement to sand mix.

NHBC are only offering to repoint and grind out to 25mm.

Long term what are implications of such a weak mortar mix?

 

[danlightbulb]

Wow sounds like a job for a solicitor.

Is the test you had done completely trustworthy - i.e accredited in some way so its valid in court?

 

[Scally-Ho]

If it's very crumbly, the I'll lay good odds that the brickwork team used washing up liquid instead of a recognised plasticiser. That horrid practice set a catastrophe waiting to happen sometime in the future.

 

[outmyway]

Yes an accredited laboratory ... detailed report etc

Would washing up liquid change the cement/sand ratios?

 

[stuart45]

All that can be done without total demolition is to rake out and repoint. A weak mortar isn't a massive issue for it's compressive strength, as many older buildings survive well with much weaker mortars. The main problem is that the surface is more affected by the weather and moisture penetration. Also, a stronger mix in the last 25mm has a different movement rate to the weaker mortar.
Adding washing liquid to the mix does not affect the sand/cement ratio, but it's not recommended in place of plaz, although the majority of big sites use mortar silos nowadays.

 

[outmyway]

All that can be done without total demolition is to rake out and repoint. A weak mortar isn't a massive issue for it's compressive strength, as many older buildings survive well with much weaker mortars. The main problem is that the surface is more affected by the weather and moisture penetration. Also, a stronger mix in the last 25mm has a different movement rate to the weaker mortar.
Adding washing liquid to the mix does not affect the sand/cement ratio, but it's not recommended in place of plaz, although the majority of big sites use mortar silos nowadays.

Thanks for that ...
It was silo supplied by CPI mortars

What about wall ties into soft mortar, will they do their job over years?

It seems the NHBC and BS guidelines aren't worth the paper they're written on.

As soon as I raise this higher though a solicitor and possibly courts then my house becomes worthless, and blighted whatever the outcome, unless its demolished.

 

[stuart45]

It's possible to renew wall ties by fixing through the centre of the face bricks. Is it timber frame or brick/block?

 

[Scally-Ho]

Just my mind whirring away in legal mode .. is the house a semi or detached?

 

[outmyway]

Just my mind whirring away in legal mode .. is the house a semi or detached?

It's detatched

 

[outmyway]

It's possible to renew wall ties by fixing through the centre of the face bricks. Is it timber frame or brick/block?

That sounds unsightly fixing through the brick faces?

It's blocks - cavity - bricks

Could the external brick walls could be demolished and rebuilt, as non structural?

 

[stuart45]

It's blocks ...

Could the external brick walls could be demolished and rebuilt, as non structural?

They can be. I've done it on a few jobs. The NHBC will do their best to avoid it if they can get away with a repoint.

 

[outmyway]

They can be. I've done it on a few jobs. The NHBC will do their best to avoid it if they can get away with a repoint.

Thanks, sounds like major works I guess not many brickies would undertake?
...the house would be unhabitable during this process with windows/doors removed?

 

[stuart45]

Brickies will do the job if the money's right. Sometimes people live in. I worked on some 30's Council houses in Moulscoomb, Brighton years ago renewing the outer skin, but they were terraced houses and done one house at a time, and then the gables, so the people stayed in.
As yours is only to the first lift, it will be interesting to see how much they are prepared to rebuild.

 

[CountryFan]

NHBC are crap imho. We had/have an issue with mould growth in our loft, I reckon it was from the wood getting wet and drying out.

NHBC (who never visited site btw) and house builders said it was because it was winter and it was condensation. We paid for extra ventilation as the "breathable" membrane imo wasn't up to the job

 

[outmyway]

NHBC are crap imho. We had/have an issue with mould growth in our loft, I reckon it was from the wood getting wet and drying out.

NHBC (who never visited site btw) and house builders said it was because it was winter and it was condensation. We paid for extra ventilation as the "breathable" membrane imo wasn't up to the job

My experience of NHBC has not been good, they are in effect an insurance company and their 'inspectors' are just lost adjustors trying to find the cheapest easiest way out.

Plus its was their shoddy building inspectors that signed off the build.

NHBC are funded by the big builders and don't want to upset them.

I think the only thing big builders are afraid of is their name in a big public court case, and the bad publicity,