Ask a Tradesman
Soft sandy mortar and other problems.
Hi, i had a small extension built by a local builder which has become a bit of a nightmare. To say pretty much everything has been done badly doesnt really cover it.
The builder has been back and made good some of the problems (or maybe the right term is made it a bit better than it was), but new problems keep coming up.
Anyway the extension was built with a lightweight blockwork. The land around is very wet and they had to pump water out to put in the foundations. It turned out they left a large hole in the foundations which meant water came into the subfloor.
They came back and dug out the foundations and filled in the hole and then put a coat of render on the outside of the foundations and some blackjack on top. They did this as all of the blockwork had been mortared very poorly and there were gaps here and there in the mortar which would also let water in.
Anyway the exterior now needs rendering so i was looking at it and have found that.
A the mortar in the blockwork is sandy soft and crumbly in places.
B the area of blockwork above the rendered blackjacked foundations appears wet and has green algae growing on it
C there is a crack running up the wall in one area that goes through the mortar and splits the blocks all the way up the wall
There is no point in moving on to put the render on if the wall is going to crumble away. I dont want to throw more good money after bad. Should i be worried about all this and what do you think needs doing to make this good?
I think the cheapest option is never the best. I do expensive quotes because there is a lot of work and skills involved in every project I take,
always ask questions and be satisfied with the answers.
Answered 23rd Oct 2013
Lots of problems:
Possible subsidence of foundation could need underpinning .
Has a dpc been put in? ,as damp rising up walling.
Was block work a 4/1 sand cement mix ?.if crumbling possibly weak mix.
Possible if on water table house constantly in water.maybe a submersible pump to drain water,when gets to a certain level.
Maybe a bitythene /primer should have been put on walling first to stop water penetrating to exterior walling.
Answered 31st Jan 2017