Protection Board For Retaining Wall?

[Spuggy]

Evening All,

Almost finished building 1m high block retaining wall in my garden. I've read through many threads on here about waterproofing prior to backfilling, and I've used the advice about Black Jack, DPM, etc on the soil side.

What exactly is 'protection board'? I know its to prevent damage to DPM sheet, but no idea what to get. The chap in builders merchants says it is those fibrous sheets; same stuff as 'expansion strips. Just checking before I buy in a load of the wrong stuff!

Cheers, Paul.

 

[Blagard]

If you google "Asphaltic protection boards" you will get info on boards specific to what you are looking for. Having said that, there are also bitumen impregnated expansion joint filler boards that may also be OK although protection is not the use they are made for. For your project, either would probably do and it may come down to availability and cost.

The Aspaltic item is most likely a special order item for larger engineering projects so not likely to be a standard stock item at your local merchants!

To be honest, all you are trying to do is to prevent backfill material damaging your waterproofing. Careful backfilling with selected material might be all you really need to do.

 

[mikric]

Polystyrene/Jablite etc will also achieve a good level of protection.

 

[macadonald]

Paul,

I had a number of threads on a similar issue last year, where I built a series of raised beds about 4ft high out of block work and then filled them with soil. A year down the line I've learnt a few lessons (in hind-sight)!

I'm glad for your sake that you decided to apply the DPC. I went with some advise that the liquid membrane (black jack) would be sufficient. My render is feelign a little hollow in places, which may or may not be a result of settlement cracks allowing moisture in.

The other thing I would have done in hind-sight is to place a damp course layer in the blocks when building. I'm guessing that damp can now easily pass up the wall and affect my render. This all only really applies if rendering I guess.

My remedial work this weekend was to painfully remove all the filled soil and line with damp proof membrane.

To stop any rising damp I am planning to drill a load of holes into the wall (7.5cm apart based on suppliers spec) and inject damp cream, which is similar to what the pro use to damp proof a house.

Just thought I'd post this for others benefit.

 

[Spuggy]

Hello again,

Thanks to both Blagard and Mikric for your help. Very much appreciated.

Thanks also to Macadonald - it may have been one of your threads I got the DPM sheet advice from in the first place. I did consider a DPC layer, but didn't do it in the end - I hope that decision doesn't come back to haunt me!

Cheers, Paul.

 

[macadonald]

Paul,

I've been doing a lot of investigation into damp creams, which are a silicon based cream normally injected into the mortar bed to stop rising damp.

To cut a long story short, I managed to get the suppliers to send me a sample, which I will be testing this weekend on a block and later placing it in water to monitor the results. I will post my findings on this forum, which may help many DIYers out there with rising damp problems.

Main reason I'm telling you is that now is the time to address this if your going to - before rendering. The experts on here can tell me if I'm wrong, but any render on a block that is directly touching the ground with no DPC, will blow eventually..