Yokel D-I-Y Heroes: No.1 PVA

I suspect – 7 months in to this project – that you can estimate how big a period restoration anyone has undertaken, by simply asking them how much PVA they’ve got through. Additional questions include “How much horsehair have you ingested to date?” or “How often – on a daily basis – do you now pick your nose?”. All three questions point to the same basic premise; the walls of old houses can be tricky beasts to tame (and generate a load of dust when fixing).

There are a number of causes for this instability; in the case of our place it is a combination of age, abuse and the amount of ordinance that was dropped in the area 70 odd years ago.

Plaster; a brief (and probably boring) history

If you’re from the UK, the way in which walls were constructed in residential properties up until pretty recently will be broadly familiar. Exterior walls of double skinned brick (with a ventilation gap between which now may or may not have been filled with cavity insulation), rendered internally. Interior walls made up of timber studwork, overlayed with “lathe”

Horse hair in amongst some slightly busted plaster and lathe in the bathroom walls (in the end this whole lot had to come down and be aquaboarded)

(thin strips of wood) and a plaster render. Older internal renders were often strengthened using horsehair as a binding agent. More recently it is a course mix of gypsum (bonding coat) with a finer mix spread on top (multi-finish). If you’ve heard people referring to having walls “skimmed” it simply means a new thin layer of multi-finish being applied to the previous layers to provide a smooth coat on which you can paint.

In theory at least, this combination of layers provides a relatively breathable surface that allows the house to expand and contract according to the climate and internal heating. It is pourous though; introduce moisture and it will quickly return to its natural state, shrink when it is dried out again and fall off the walls.

We’re a pragmatic lot here in the UK. Our solution to the ravages of time causing plaster to become unstable, crack and look a little less than flat is to cover it with paper (wallpaper or lining paper that can then be painted). Not only does this flatten the surface, but also allows a degree of further temperature expansion.

Fashion vs Practicality 

Probably as a result of being a child of the 70’s, I’ve always hated wallpaper and lining paper. I grew up in houses that had Anaglypta on the walls, and later rented many places with the horrid “wood chip” style version hiding what I now know is a multitude of sins. In my first ever “home of my own” (a super cheap ex social housing flat), I gradually removed it all with the use of a steamer, repainting it directly onto the plaster.

Wallpaper in general has now become something that is applied primarily as a stylistic

Exposed lathe in bathroom, with some removed due to rot. As a result we covered in acquaboard (waterproof plasterboard) before it was re-plastered, to protect the timber

effect, contemporary building use wall systems (where metal studwork is bolted into place, and plasterboard can be simply slotted into place, secured and decorated) which are quicker, simpler and less material intensive to construct. I’ve lived in a couple of modern places that were built using this way; they are great unless you actually want to say, hang a picture or put up a shelf. In that case you’ll be spending a deal of time with a stud detector, plasterboard fixings and inevitably, filler and paint.

When people say “they don’t make houses like they used to”, they’re right. There’s a good reason for that. As attractive as the older, almost agrarian approach to construction is, it had moved on little from medieval practices. Lathe and plaster? It’s wattle and daub with a slightly better finish and middle-class pretensions.

So, why PVA?

This house was built just in the Edwardian period, around 1905. By the time it was built, it was a style that was already deeply unfashionable. Indeed, houses of this style only really started to treated with any degree of reverence again in the 1980’s, as a trickle-down effect from the D-I-Y preservation pioneers of the 60’s and 70’s who saved whole swathes of British city’s more elderly housing stock.

I’m no romantic when it comes to architecture; when I’m reminded of building we have lost in London, I mourn Mondial House rather than Euston’s Doric Arch. I still believe that in a few decades, Portsmouth (where I went to school) will begin to regret what it did to The Tricorn Centre. These were all one off constructions; here in East London there are row after row of identical terrace houses such as ours, build to house the workers from the Royal Docks expansion.

Having said all of that, we’ve both been as keen as possible to preserve as much as is left of the original house. Due to the battering it had, we have lost quite a lot of the original interior wall render in the bathroom and the smallest of the bedrooms. Elsewhere, there is an ongoing battle to save what is left and that brings us  – eventually – to PVA. See, I got there in the end.

Restoration of a house like this works in the following way.

  • Carefully remove lining paper
  • Hope beyond hope that behind it, the render is solid
  • Render falls on floor

As a result you end up with a patchwork; solid render, broken render and at times, no

An example of patchwork walls from the master bedroom; bare lathe, exposed render and plaster

render at all. Right now we’re working on the master bedroom and it is a case in point of that problem. The internal walls have original render that is very unstable, some of the external walls to have lost render, but as they are set against brick what is left is solid enough. That which is on the lathe though – which bends to the touch, what with only being thin strips of wood – risks falling off entirely.

There is a solution to this and it’s a simple, cheap one. 3 parts PVA to 1 part water, carefully apply with a brush and leave to go off (or, if you’re not somebody who pretentiously wishes to sound like a professional, “dry”). As if by magic you’ve got a solid enough surface, to skim over the top.

So, after all that, that’s all the advice there is?

To be honest, yes. PVA solves 99% of your plaster instability issues (not least being the bonding coat that you’ll use when skimming too, as well as being a decent glue and a refreshing summer drink*). HAIL THE MIGHTY PVA.

* Please don’t try that last solution, it is a joke and I take no responsibility for any PVA drinking.

About Matt Hero

Thinking global, acting yokel
This entry was posted in D-I-Y and tagged , , , . Bookmark the permalink.

One Response to Yokel D-I-Y Heroes: No.1 PVA

  1. Pingback: Yokel D-I-Y: Plastering. Is. Hell. | Yokel Hero

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