Waterproofing a porous wall

[Sherlock]

The grainstore on a block we contract farm is porous spoiling grain, we'd like to waterproof it and agent suggested to attach some damp proof membrane to the wall, I have concerns with this as it will probably be a haven for rodents.

Is there a spray-on type product we can use.

The wall is concrete filled breeze blocks and floor level outside the shed is higher than internal floor so external waterproofing isn't possible

 

[Ffermer Bach]

I would render the wall inside with sand/cement (and water proofer), maybe two thin coats then paint on feb tanking on top of the render, and if I wanted belt and braces, maybe french drain outside the wall too.

 

[Ffermer Bach]

and paint on SBR to the blockwork before rendering

 

[Grassman247]

Just fibreglass the wall to seal it

 

[Wurzeetoo]

How much higher is the external floor? And is it a finished pad right upto the back of the building? Or just mud?

 

[Zebbedee]

I would lower ground level if possible

 

[Still Farming]

Palace tanking solution use to be good?

 

[DrWazzock]

We have lined places like that with black polythene silage sheeting (new). Screw a lat along the top of the wall to hold the polythene and let it hang down the wall like a curtain with another 6" coming away from the wall across the floor. No space for rodents, quick an easy to fit up, 100% waterproof, food safe and has lasted years. Just don't rip it with the bucket. Sometimes need to make sure it's nicely flat against the wall when tipping. Seal joins and corners with agritape. Jobs a good'un.

 

[RushesToo]

@Sherlock As the outside is higher you will find it hard to stop water coming through - it should have been waterproofed outside then built.

This needs checking as it is just logic not tested. The water will always leak through and will always head down. I would think a channel grooved in the floor around the edges to lead the water away and covered with fibreglass to the height of the outside wall and over the channel would have a chance.
You would effectively be making the outside wall the sacrifice and protecting the inside by channelling the water away. You must be able to wash it through or it will just overflow into the floor.

It is the old story, do it right, do it once. It wasn't right and you will be messing with this for a while. I feel for you.

 

[Sherlock]

As said in opening post that ground level outside is higher than internal floor, outside is a neighbours adjacent shed (the farm used to run as one, is now split) so the external height of earth/stone cannot be altered

 

[David.]

Get some 300mu damp proof membrane sheet and batten it as the good Doctor advises above, no void for vermin to get in.
In any case, it looks like a few mice are the least of your problems.