1930s house, mortar is falling out like sand under DPC!!

justmerob · Post by **justmerob** » Fri Feb 27, 2009 8:23 pm

Thanks for reading!

We have a half head height space under the house I have started using for storage. The wall along the back of the house under the DPC level has worried me for some time. The mortar between the bricks is/has been falling out, just like sand.

Two or 3 years ago we had cracks at the back of the house dealt with via the insurance company who treated it as subsidence due to tree roots and we had trees cut down in the back garden. I understand the insurance chap went under the house and spotted no problems.

I suspect the issue with the mortar is due to damp from an overflow which had been left for some time but now sorted and poor quality mortar.

My elderly parents own the house and really don't want to know, they just want a quiet life.

A builder chap told me to just re-point it. So my question is, is he right or should I push my parents to agree to get the insurance people to look at it?

opinions appreciated!

Gadget · Post by **Gadget** » Fri Feb 27, 2009 9:15 pm

Re-pointing will certainly stop the mortar falling out so I guess it's best to get it done, even if it's just for your parents quiet life.

leebwk · Post by **leebwk** » Sat Feb 28, 2009 2:36 pm

Hi,

Re-pointing is the only thing you can do and this will be more than adequate, make sure it is well raked out ie 25mm depth and pointed with a strong 3:1 mix everything will be fine

vespa · Post by **vespa** » Sat Feb 28, 2009 4:10 pm

leebwk wrote:Hi,

Re-pointing is the only thing you can do and this will be more than adequate, make sure it is well raked out ie 25mm depth and pointed with a strong 3:1 mix everything will be fine

1:1:4 mix..? I do believe the mortar shouldn't be stronger than the bricks..?

justmerob · Post by **justmerob** » Sat Feb 28, 2009 7:21 pm

thanks very much for replies, appreciated

yeah, i was thinking of a rich 1:3 or 1:4 mix.

i worry that if i rake out too much it could cause things to start moving, with the weight of the house above. maybe i should do it a section a day or something?

and spray the dusty bricks with water so the new cement forms a good bond?

Gadget · Post by **Gadget** » Sat Feb 28, 2009 9:19 pm

Yes, keep the bricks damp!

justmerob · Post by **justmerob** » Sun Mar 01, 2009 7:11 pm

okay, thankyou

vespa · Post by **vespa** » Wed Mar 04, 2009 5:49 pm

justmerob wrote:thanks very much for replies, appreciated

yeah, i was thinking of a rich 1:3 or 1:4 mix.

i worry that if i rake out too much it could cause things to start moving, with the weight of the house above. maybe i should do it a section a day or something?

and spray the dusty bricks with water so the new cement forms a good bond?

1 lime, 1 cement ans 4 sand. The lime will help with water run off

justmerob · Post by **justmerob** » Wed Mar 04, 2009 8:41 pm

its on the inside face of the wall, so I like to think water run off won't be an issue :)

Thanks guys for your comments, genuinely appreciated,

vespa · Post by **vespa** » Thu Mar 12, 2009 9:27 pm

justmerob wrote:its on the inside face of the wall, so I like to think water run off won't be an issue :)

Thanks guys for your comments, genuinely appreciated,

you still get water run off under a house/cellar etc. Lime soaks in water and allows it to evaporate, it breaths. So in a damper enviropment lime would be the way to go...

justmerob · Post by **justmerob** » Fri Mar 13, 2009 12:11 pm

ok, thanks, i'll ask for it when i buy the materials next week

leebwk · Post by **leebwk** » Fri Mar 13, 2009 1:50 pm

vespa wrote:
leebwk wrote:Hi,

Re-pointing is the only thing you can do and this will be more than adequate, make sure it is well raked out ie 25mm depth and pointed with a strong 3:1 mix everything will be fine
1:1:4 mix..? I do believe the mortar shouldn't be stronger than the bricks..?

I think you will find that all work below DPC used to be 3:1 with no additive and certainly not 1 lime per gauge
A small amount of plasticiser is acceptable

leebwk · Post by **leebwk** » Fri Mar 13, 2009 1:51 pm

vespa wrote:
leebwk wrote:Hi,

Re-pointing is the only thing you can do and this will be more than adequate, make sure it is well raked out ie 25mm depth and pointed with a strong 3:1 mix everything will be fine
1:1:4 mix..? I do believe the mortar shouldn't be stronger than the bricks..?

I think you will find that all work below DPC used to be 3:1 with no additive and certainly not 1 lime per gauge
A small amount of plasticiser is acceptable

vespa · Post by **vespa** » Fri Mar 13, 2009 3:52 pm

leebwk wrote:
vespa wrote:
leebwk wrote:Hi,

Re-pointing is the only thing you can do and this will be more than adequate, make sure it is well raked out ie 25mm depth and pointed with a strong 3:1 mix everything will be fine
1:1:4 mix..? I do believe the mortar shouldn't be stronger than the bricks..?
I think you will find that all work below DPC used to be 3:1 with no additive and certainly not 1 lime per gauge
A small amount of plasticiser is acceptable

In the 1930s DPC was in the main engineering bricks... Lime IS a plasticiser...

"The glazed bricks were also called engineering bricks in the 1930’s. These glazed or very high-fired
bricks have a matrix that is almost glass, resulting in almost no open porosity and permeability in order
to prevent rising damp"

http://209.85.229.132/search?q=cache:ZQ ... =firefox-a

This link may help.

http://www.ibstock.com/pdfs/get-it-righ ... right7.pdf

justmerob · Post by **justmerob** » Fri Mar 13, 2009 7:50 pm

the bricks in our house are defiantly not glazed (the houses weren't built very well), i remember the ones you mean though, the basement in my old junior school had them, dark brown i think they were