Repair Cracks in Cement Rendering

[Davidm]

Victorian semi, large south facing wall, smooth rendered and painted. Has some cracks that need repairing before I repaint it. The cracks aren't huge, 1-2mm wide, probably full depth of render. Just caused by natural movement from the heat of the sun, most of the neighbours walls have the same problem, and surveyor says nothing to be concerned about. No point in filling with mortar, it will just crack again.

Was thinking of doing the following:

Brush out any loose render, dust etc Apply some stabilising solution/sealant, or maybe diluted pva? When dry fill with paintable flexible frame sealant? Use wet sponge to blend in and slightly stipple the surface Paint with regular Sandtex or similar.

Does this seem reasonable, or any better suggestions?

[tabbypurr]

You could fill with pretty much anything.

NT

[The Natural Philosopher]

decorators caulk. Its waterproof enough if painted.

[tabbypurr]

I wouldn't, but you could

NT

[Brian-Gaff]

Have you tapped it to see if its blown, ie hollow sounding and hence no longer attached to the underlying wall. It might not be what you want to hear, but I had to have several feet of this removed and re rendered as nothing was holding it on in some places. One supposes it was water getting behind it and freezing etc. Brian

[Davidm]

It's not blown - yet, which is why I want to repair it now before the water gets in and freezes.

[stuart noble]

Most things aren't fine enough to penetrate a 1mm crack (certainly not mortar) but the 2 part Profil from Toolstation works pretty well IME

[JimK]

/Does this seem reasonable, or any better suggestions? /Q

1-2 mm? Paint em closed w the masonry paint?

Can't see how anything (especially 2 part filler) is going to penetrate any further than a few coats of paint? Never mind being up a ladder...

Jim K

[stuart noble]

The filler I referred to is of a particularly fine consistency

[JimK]

"EVERBUILD PRO-FILL is a 2 part high performance multi-purpose filler, cons isting of a grey coloured polyester paste with a Benzoyl Peroxide hardener. When cured, PRO-FILL forms a strong hard mass which offers excellent abras ion resistance and durability. PRO-FILL is suitable for use on timber, meta l shuttering, concrete and GRP Specification BENEFITS;

- Simple to mix.

- Impact resistant.

- Fast curing.

- Water and oil resistant once cured.

- High strength. "

Sounds exactly like car body filler..

Wonder how much cracking you'd fill after you got up the ladder before it a ll cured on you?

Nah

Jim K

[stuart noble]

Er, well, it's best not to mix it all at once! Cures with any amount of hardener, so no need to be too accurate. Yes, same as car body filler, but cheaper, and I would guess has a higher resin to aggregate ratio. Not a good idea to have a pale coloured hardener though. Red would have been better.

[Davidm]

High strength - just what I don't need, or within a few months there will be new cracks opening up as the wall continues to move.