damp proofing breeze blocks

[mike49]

The porch on my house has been built of breeze blocks (hollows) forming an 11" cavity wall laid directly onto a concrete slab. Each leaf of the wall sits directly on a 150mm dpc strip - i.e. not on a raised row of bricks. As a result, water seeps across the base of the outer blocks, above the 'dpc', and into the inner ones. What is the best way of damproofing the inner wall, or more precisely, will silicone cream injection work to form an impenetrable layer above the existing dpc? Cheers!

 

[PrenticeBoyofDerry]

I think the best route would be going down the injection path,
you can buy the DIY creams not sure of there success rate though,
or employ a pro.

 

[mike49]

Thanks for that PBoD, but still not sure about injection cream. Read on one of the sites that it wasn't suitable for breeze blocks "because they are porous!" ... that must have been a misprint, surely? Know anyone that has used it successfully on hollows?

 

[hotrod]

Read on one of the sites that it wasn't suitable for breeze blocks "because they are porous!"

All masonry is porous to a lesser or greater extent.

The porch on my house has been built of breeze blocks (hollows) forming an 11" cavity wall laid directly onto a concrete slab. Each leaf of the wall sits directly on a 150mm dpc strip - i.e. not on a raised row of bricks. As a result, water seeps across the base of the outer blocks, above the 'dpc', and into the inner ones.

I am having difficulty visualising this - any chance of a photo? Damp proofing the inner leaf should be straight forward, even more so if you have a clear cavity, but I just want to get your detail correct in my mind before I suggest any solutions.

 

[mike49]

Not quite a photo but should give you a good idea of the problem!
View media item 19379 [/img]

 

[noseall]

Not quite a photo but should give you a good idea of the problem!
View media item 19379 [/img]

This is a very poorly thought out design and i have ranted about it quite a few times on this forum.

It always throws up the same water ingress problems.

When will people learn.

 

[mike49]

Thanks noseall, but is there a solution that doesn't involve me taking out the bottom row of breeze blocks (bit by bit) and inserting a proper dpc? i.e. will injection cream do the business???

 

[hotrod]

Difficult one because the DPC is in the wrong place. You could try and render to GL externally and then form a some type of concrete fillet (say 50mm x 50mm) to fall away from the wall. Render internally and then gypsum plaster to finish???

 

[Nige F]

Totally "off the wall" idea If the porch floor can be uncovered and left - wait for summer ..Drill holes in inner wall @ a downward angle - and pour Grangers` fluid or other waterproofer in through a funnel and a bit of hose. It`l lay where the water lays now @ the bottom and possibly do the same job as fancy injections. OR stink you out

 

[Blagard]

The only none destructive solution I can think of is fit an external flashing (a bodge to fix one!) Since the source of the problem seems to be the rain running down the face onto the crap DPC arrangement you need to intercept it and get it below the step the DPC sits on.

Fit a flashing to the external wall and dress it down over the DPC and over the edge of the concrete slab. What you flash it with I will leave to you since I always chase out and fit lead or other "proper" flashing. You might try the horrible self adhesive flashband if it is still around.

 

[gregers]

is the example you have posted the actual construction as your porch?
if so then clear the cavity and inject the inside skin?
or why dont you just black jack the inside?