DIY Doctor

Advice on concrete block house and incorrect dpc

Postby Bri44 » Mon Oct 05, 2020 10:14 pm

Hi all.
My house is a cavity wall concrete block construction and rendered. The house is 7 years old.
Cracks appeared that have been caused by incorrect expansion joints and a DPC installed halfway up the house.
A structural engineer advised the DPC needs removing and the expansion joints corrected.

All the render has been removed by the developer.
It was tough to come off.

Looking at the blockwork it has many vertical bed joints that are 40mm wide, some gaps that have a stuffed part block in are 50mm wide. The mortar is weak. I can rub it out with my finger.
The render removal has pulled lots of mortar out leaving holes. Looking in the holes the mortar on goes back an inch or so with no mortar any further back.

I also have what appears to be another DPC sitting on a sandstone ledge that goes around the house. It goes right through and then up the inside of the block. The first picture shows this. Second image shows the mortar joint only going back an inch or so and third image shows a section of blockwork

Should I be concerned about this mortar and the size of the joints?

I don`t want it rendered over if it's not correct.

Thanks
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Bri44
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Postby stoneyboy » Tue Oct 06, 2020 10:56 pm

Hi bri44
Presumably the surveyor saw the house before the render was removed. If so you need to get him back pronto!
Regards S
stoneyboy
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Postby Bri44 » Tue Oct 06, 2020 11:34 pm

Yes he saw it before the render was removed. I’ve requested he come back.

What are your thoughts in the mortar joints and the other DPC that is attached to the inner blocks and reaches over and under the outer block wall creating a sealed barrier in the cavity?
Bri44
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Postby stoneyboy » Wed Oct 07, 2020 8:35 pm

Hi bri44
Don't know whether you are in an area that would know the term 'bodge job' but that is what it is. It doesn't take much in the way of skill or tools to cut a concrete block so the wide perps are difficult to explain.
The presence of a DPC half way up the wall would suggest the top half of your house was going to be tile hung or clad. You will have to get your surveyor to explain why it needs removing.
Regards S
stoneyboy
Rank: Project Manager
Posts: 3661
Joined: Wed Dec 10, 2008 6:44 pm



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