Rendering at Holton Heath

Tapping the whole elevation. The survey is a light hammer over every square metre, including the parts you cannot see from the ground. Sound render rings hard. A hollow note means the coat has delaminated from the background and nothing put on top of it will hold it there. We mark the areas, photograph them and measure them, and that measurement is the decision.

The overlay. Where the existing coat is stuck and reasonably flat, the wall is cleaned down, any loose patch cut out and made good, a stabilising primer applied as a key, and then a mesh reinforced polymer basecoat is worked over the whole elevation before a through-coloured silicone topcoat scraped to a fine texture. The mesh is the point: it ties the new coat across the old cracks so they do not print through within a year.

The strip out. Where more than roughly a third of a wall is hollow, we hack off to the blockwork, clean down the background, cut out loose mortar and any spalled face and let it dry. It is more work and more waste, and it is the cheaper answer over any sensible timescale once a coat has genuinely started to let go.

Beads and stop ends. Either way the edges are rebuilt: angle beads on every corner, stop beads at reveals and against frames, a bellcast at the base so water is thrown clear rather than tracking back underneath. On an overlay the render is now thicker, so the beads, the sills and the pipework all need setting out again, and that is the detail cheap overlays skip.

Monocouche, sand and cement and dash. Monocouche is a single thick through-coloured coat for new blockwork and extensions. Traditional two coat sand and cement, scratched and floated, still belongs on plinths, garages, chimneys and boundary walls, and takes paint, dry dash or a Tyrolean finish. Pebbledash with a sound backing can be stabilised, patched and re-dashed to match rather than stripped.

Cracking and staining. Fine crazing across a panel is shrinkage in the coat and is a good candidate for an overlay. A single crack out of a window corner is movement in the building and wants understanding before anything covers it. Green streaking is algae and only wants washing.

Render over external wall insulation. If you are going to disturb the elevation anyway, EWI board with a render carrier or a mesh basecoat is worth pricing alongside a plain overlay, and the thermal gain depends on the sill, eaves and base detailing rather than on the board thickness.

No rate per square metre, because the square metres are the easy part; what is already on the wall decides the price.

Getting to it. A modern detached with a wide side access, a semi with a garage between it and the fence, and a bungalow behind a conservatory are three different platforms. A bungalow gable comes off a tower, a three storey elevation wants a scaffold, and the platform has to stand for the whole system rather than a day. The work at height rules are why it is a priced line rather than something folded into a rate.

What is already on the wall. Rendering over sound brick is one job. Hacking off blown sand and cement, or a pebbledash that has parted from the background, is another, and it is the part nobody can see from the road. We tap the whole elevation before quoting, because the hollow areas set the hours.

The system, and what the wall behind it needs. Silicone thin coat over insulation, monocouche through-coloured, or traditional sand and cement all price differently and behave differently. On a solid wall that has to breathe, a plastic-rich modern system traps moisture and moves the problem inside, so the right system is a wall decision rather than a colour decision.

Comparing quotes? Ask which system is being quoted and how many coats, whether the old render is being hacked off or overlaid, whether beads, bellcast and stop ends are included, whether the scaffold is in the price, and what happens to the existing sills and pipework. Two quotes for the same job are usually two different jobs.

An overlay is genuinely attractive on eighties and nineties blockwork. There is no strip out, so no skip and no week of noise. The wall is not exposed to the weather halfway through. And a mesh reinforced basecoat over a sound existing coat gives you a finish that behaves like a new system, because the flexible part of it is the part that faces the weather.

What kills it is a hollow background. If the old coat has parted from the block in patches, then whatever you put on top is now bonded to something that is itself hanging on the wall. It will look right for a year or two, and then the loose area behind it will move and take the new work with it, in a bigger sheet than would have come off on its own. That is why the tapping matters more than anything else in the quote, and why we do it before we talk about colour.

The rule of thumb we work to is a third. Below that, cut out the failures, make good, and overlay the whole elevation with mesh in the basecoat. Above it, take the lot off. If someone quotes you an overlay without having gone round the wall with a hammer, ask them how much of it is hollow. If they cannot tell you, they have priced a guess, and you will find out which way it went in about three winters.

We cover Holton Heath, Sandford, Lytchett Minster, Wareham, Upton and the BH16 addresses around them, under Dorset Council. You are dealing with Bournemouth Roofing & Building, the trading name of Bournemouth Roofing & Building Ltd, registered in England and Wales, company number 15471719, which you can look up in a minute. Thomas Hannen's business, and he is the one who comes out to price the job, not a salesman. A verified customer's 10 out of 10 on Checkatrade. The visit and the written quote are both free.