Render repair and silicone render in Harrow

Cracked render is a symptom, not the diagnosis

A crack in a render finish can mean very little or quite a lot. It might be the render itself giving up after decades of frost and heat. It might be water tracking in behind the finish from a failed sill, a blocked gutter or a leaking downpipe. Occasionally it points to movement in the structure underneath, and no amount of surface repair will hold if that is the case. The only way to tell the difference is to look properly, which is where we start.

What we look for on a Harrow survey

An inspection takes in the whole elevation, not just the crack you can see from the pavement. We tap the render to find hollow areas, check where water is getting in and look at how previous repairs have behaved.

• Hairline crazing across the surface, and wider structural-looking cracks
• Blown or hollow render that has lost its bond with the wall behind
• Green and black staining, usually a sign of persistent damp or poor drainage
• Failed patch repairs, including colour-matched attempts that have since cracked round the edges
• Sills, copings, gutters and downpipes, which cause more render failure than the render itself

We inspect before we quote. If the cause is a leaking gutter rather than the render, we will tell you that.

Repair, or re-render?

This is the question most Harrow homeowners actually want answered, and it is worth being straight about it.

A repair usually makes sense when the damage is contained, the rest of the wall sounds solid, and the cause is something that can be fixed at the same time. Localised patching is cheaper, quicker and needs less scaffolding.

A fuller approach usually makes sense when cracking runs across the whole elevation, when large areas sound hollow, when the render has already been patched more than once, or when the wall behind is a solid brick wall that would benefit from being insulated at the same time as it is refinished. On a solid-wall home, re-rendering is often the moment to consider external wall insulation, because the scaffolding and preparation are already paid for.

Silicone render in Harrow: one job from start to finish

The house in the photos on this page is a Harrow mid-terrace. Its pebbledash was cracked across the front and hollow in several places, and it had been patched before. Another patch would not have lasted, so the owners chose a full re-render.

We hacked the old pebbledash off back to the brick, protected the windows and door, and dealt with the sills where water had been getting in. The wall then went back in a through-coloured render system with a coloured silicone finish. Because the colour runs through the finish, it does not need painting, and a silicone finish sheds rain well, which matters on a front elevation that faces the weather.

Is silicone render right for your house? It suits most Harrow semis and terraces once the old finish is off and the wall is sound. On a solid brick wall it is also worth asking whether to add insulation under the new render, because the scaffolding and preparation are the same either way. We set out both options in the written quote.

How the job runs

A surveyor visits, inspects the elevations and talks through what they have found. You get an itemised written quote covering preparation, the repair or system proposed, detailing around windows and sills, and scaffolding where it is needed. On site we cut out failed material back to a sound edge, deal with whatever was letting water in, and rebuild the finish. There is a clean-down at the end of each day, and sign-off with warranty paperwork at the end of the job.

Harrow render questions