Substrate preparation

Waterproofing of building parts in contact with the ground


BOTAMENT building sealants are suitable for all mineral substrates. So that structural waterproofing bonds properly with the substrate it is of paramount importance to prepare the substrate thoroughly. First remove any concrete nibs, honeycombs, mortar lumps, and all other loose bits and separating substances. Unevenness, indentations and defects of a depth of up to 5 mm can be covered by the sealant itself. Larger defects and break-outs can be made good using our levelling mortars BOTAMENT M 90 or M 36 Speed, which can also be used to close open butt joints and bearing joints within the brickwork. After that priming can be carried out using BOTAMENT BE 901 Bitumen Pre-coat or, if the substrate is very absorbent or crumbling, BOTAMENT D 12 Deep Silification. 

 

Porous substrates and substrates with blowholes, such as concrete and pumice stone, must receive a scratch coat from the structural waterproofing system chosen prior to applying the first waterproofing layer so as to minimize blister formation.   

All substrates must have sufficient strength and stability and at the time the waterproofing works are carried out must ideally be dry or only just slightly damp and must be frost-free.

Expert Tip:

Substrate inspection


Swipe test:

When swiping with a finger over the surface no particles should come off.  

Scratch test:

The surface is scratched in cross-hatch pattern with a metal tool such as a screwdriver, knife or nail. The deeper the scratch the lower the strength or stability of the substrate. Any break out at the edges of these ridges and at the crossing points can also give helpful clues about the substrate's stability.  If bits break off or the nail is able to penetrate, any loose layers must be removed. Porous concrete and crumbling substrates should first receive a deep-silification treatment.

Wetting behaviour test:

Water applied to the substrate ought to be absorbed very quickly. Surfaces with a wet sheen ought to be avoided; a slightly damp substrate can be worked over without problem.

1

Remove all loose particles and chamfer the foundation (border/edge).

2

Chamfer the outer edge of the brickwork. 

3

Protect the base from negative water pressure with BOTAMENT M 34 or MS 30  

4

Repair defects and break-outs level with the surface with BOTAMENT M 90 or M 36 Speed.

5

Prime with BOTAMENT BE 901 Bitumen Primer.

6

Prime with BOTAMENT D 12 Deep-Silification.

7

Produce a  coving with BOTAMENT M 36 Speed.