Monday, 16 November 2015

WoodWool and woolwool walls (internal insulation done proppa)

Taking the walls back-to-brick in some areas has revealed a catalogue of catastrophic cock-ups at The Lodge.

In particular the building, it seems, has been beset by damp problems over the years, not least in the Living Room, the dog-leg of which is now known globally as The Pantry.

In stripping off The Pantry's wall coverings we managed to find almost another foot width-ways and 6" on the north wall, such were the layers of failed remedies and ignorance. Behind a gypsum skim was plasterboard, behind which was battening, underneath which was a thick plastic sheet, behind which were a few more layers of gypsum in one form or another. Those surfaces were individually 'decorated' with an eclectic mix of hideous wallpapers and insipid paint layers to boot. Beneath the layers on one wall we found a gloss-painted 10" wide, floor-to-ceiling upright from the door frame back when it was a bona fide pantry. And on one of the walls in the main room we discovered, underneath another plasterboard layer, floor-to-ceiling corrugated bitumen sheets hammered into the brick with dozens upon dozens of nails.

Given the amount of mould and wrinkly wallpaper in the Living Room when we first set eyes on the place, none of the supposed remedies had worked so a new way of thinking was required.
As with the rest of the building, we decided that if we can't keep the moisture out then we'll have to find a way of working with it - by our rules.

And this meant harking back to Ye Olden Days when the house was first built and learning about how it managed it's environment. There were no waterproof building materials like gypsum plaster and cement in the late 1700s and early 1800s, so it was constructed in a way that worked with the moisture rather than against it. 
That means from the ground up, so attempting to encase the house in an unnatural waterproof protective bubble is always going to fail because it's impossible unless you plan to knock the whole thing down and start again. And shame on you if you're that person. Get out of our blog.

As I've said many times before here, the main player in working with moisture in an old house is lime. Lime plaster. Lime mortar. Lime pointing. Lime cheesecake.

Lime allows moisture in through beyond its surface, then allows it out again over time. It breathes, whereas modern materials like plastic sheeting or gypsum plaster don't - they trap water.
If you have lime pointing already (if you have cement, that's bad news because it cracks) then moisture comes in from the outside gradually, as it should, but stops when it meets the plastic barrier... it's got nowhere to go so it'll stagnate and maybe seep through a staple hole or two, keeping the corner behind the TV a bit squishy.

Wrinkly wallpaper in the Living Room caused by
moisture sitting on the gypsum wall and bad air flow
Likewise moisture inside the building from the likes of cooking, bathing and even breathing hits the first layer in your gypsum-clad living room and if it's cold enough it'll just sit there being all damp and causing mould on the wall behind the settee or peeling wallpaper behind your bookcase. This is made even worse if you don't open the windows regularly, causing poor airflow.

Incidentally, if this is happening to you and the "expert" that Facebook strangers tell you to call round to look at it pokes the wall with a two-pronged moisture meter and says you've got rising damp then thank him for his time, slam his hand in the door and sic your chihuahua on him. You probably haven't - those probes are for use on timber only because they're meant to poke in to the surface and they can't do that with plaster so they only measure the moisture that has settled on the very top, rather than test inside the actual wall itself. I've been reliably informed that many so-called 'professionals' have this habit. They make their living installing damp-proof courses.

So anyway, where was I? Yes, it was time to go back to basics.
We bought a load of 2.4m 3x2 CLS timber at something like £2.50 a length from our local builder's merchant and Terminator Trevor and I set about installing new battens on the two external walls that form part of The Pantry.
Terminator Trevor's version of a tea break
(the Kingspan is for the shed, not the house!)
The problem here is that I'm rubbish when it comes to fitting Rawl plugs and screws in to freshly-drilled holes in masonry.
I know the principle, of course, but when it comes to my brain putting everything in to motion I usually end up covered in brick dust and despair. That's why Trevor was on-hand to give me a lesson in what should be a Basic Man Skill for most other people.

We got to sawin' and a-drillin' and a-screwdriverin' and over the course of a couple of days and many hot beverages we got the basic batten framework all measured-up, cut and secured firmly to the wall. In the process we discovered that the walls are pretty much square which made things much quicker and easier.

That done and with Trevor off rescuing old ladies from trees and catching bullets with his teeth it was then up to me to start on the insulation. We're using all natural and breathable sheeps wool, although I haven't yet found out definitively if it's sheeps wool, sheeps' wool or sheep's wool with an apostrophe thrown in somewhere.

The clocks going back has made for some nice moody
photos lately. I approve of this.
I'm digressing.
Despite the walls having been very cooperative so far there were still lots of gaps behind the woodwork and in various holes here and there.
So using a short thin length of sawn-off lath from the ceiling job (I haven't tidied up from that yet) I tore small pieces off the roll of wool and jammed it in to the gaps for all I was worth.
Several hours, three small blisters on the palm of my hand (I somehow forgot about gloves) and what felt like a mile of wool later, that was done. Sadly I had to fill in the four square half-brick holes in the west external wall that seem to have had a purpose in The Pantry. I had wanted to keep them visible as a curiosity but there was no way to lime plaster around them without leaving a pretty large uninsulated area that would've acted as a heat sink and they were too small to actually be useful. So we decided to cover them up. Shame. I popped a wee note in one for someone wearing hoverpants to discover in 100 years though.

The purpose of filling these holes, by the way, is to eliminate as many small air gaps as possible. Although not a major player in the damp thing, there's still a chance that moisture breathing through the rest of the natural materials will hit an air pocket and, if it's cold enough, condense. So better safe than sorry. And it'll be a tiny bit warmer too, which can only be a bonus.

The room really does smell a bit like sheep
now and I'm told it gets stronger when it rains.
Next came the insulation proper.
After SausageTheCat bribed us in to donating a significant length of wool to him for his bed by constantly lying on top of the roll as we were using it, Dawn and I hung great lengths of 50mm natural lagging down the walls between the precision-spaced battens, down to the floor. These were tied with string to nails in the wood in three or four places on either side of each length to stop them sagging both while we were working and for when they're beyond reach behind the final layers.

Finally (this is over the space of a good few days, by the way - I'm not a ruddy machine), it was time for the final layer, ready for the plasterer.
We had sourced something called WoodWool from an excellent company called Lime Green in Much Wenlock, and because we needed advice about a few things we headed over there and loaded up the car with 20 big boards after having a good old chat for half an hour.

Another natural insulator, WoodWool is basically a load of grated wood thrown in a pot along with some lime, brought to the boil and formed in to pre-cast sheets before drying. Maybe I'm oversimplifying it a bit, but the boards are thick, dense (albeit crumbly at the edges and corners), insulating and breathable. And you can cut them with a jigsaw set up for wood.

From left: wall, woolwool, WoodWool
Another skill I'm sadly lacking in is visualising angles when cutting things, as demonstrated in the shed where I've been sawing and fitting 120mm Kingspan insulation around awkward braces. It's like a game of drunken Jenga with almost as much vomiting afterwards.

So it may have taken three times as long as it should have, and I might have stood stock-still and unblinkingly staring at the walls while I waited for my brain to say something too many times, but I finally got the wool and battens clad with nice and tidy edges around the windows and surprisingly few chasms between the boards. Unlike the wool, which will breathe faster, I haven't dropped the boards to the floor to stop them wicking any damp from the quarry tiles because that would eventually make them fall apart, but it means slightly easier cable access and the voids will be packed out with more wool before new skirting is fitted (note to self: start thinking about skirting boards).

The window reveals will be plastered straight on to brick because insulating them would narrow the openings although
at some point we'll be getting insulated oak sills to cover the two original sandstone ones which are too short
and have been damaged by someone screwing straight in to the stone and cracking both for the sake of cheap ply sills.
The 'orrible uPVC windows, of course, will be changed one day.

After a quick tidy-up I turned my attention to the oriel window (which sounds poncey - it's a bay window) at the front of the Living Room on the south-facing wall.
Last month I pulled down the suspended ceiling in there to reveal four mouse skellingtons and some nice timbers directly underneath the tiled roof, which we then had blasted. We quickly decided that we should keep that area open as another feature, but that meant insulating it because it was pretty cold and drafty when the winds were up a day or two ago.

It's an awkward space to photograph...
imagine this finished: that's how it looks
But being a pitched roof featuring angled rafters forming six different-sized triangles and awkward shapes - and us wanting to keep the rafters on show - if I thought doing the walls was a Krypton Factor test I was ready for a different level altogether. I even caught myself uttering the word 'hypotenuse' at one stage. I had to sit down.

So I cut a couple of dozen 2.5" lengths of 1x1 wood that had been donated by my dad on my folks' last visit and screwed them to the sides of the joists to act as both spacers from the underside of the tiles and support for the WoodWool segments I had still to measure-up and cut.
For the most-part this was much simpler than I expected (measure; measure again; stare at it for a bit; sharpen pencil; draw straight lines; drink coffee; go back and check measurements; scribble everything out and draw it again; cut with jigsaw; count fingers) and it was pretty straightforward if a little time-consuming. And the gaps aren't too big.

The underside of the tiles was packed out extra deep with s'hee'ps wool then the boards were screwed firmly to the little battens. Because of the roof pitch the boards don't reach down to the top of the window frame, which concerns me slightly, but that will somehow be tidied up before the boards - and the walls - are lime plastered then had some breathable paint thrown in their general direction (note to self: no girly colours - let Dawn choose).


  1. "corrugated bitumen sheets hammered" that could be Newtonite Lath, a pitch-fibre sheet invented by John Newton in 1937.

  2. Gypsum plaster does breathe a little or just not very well and eventually disintegrates when too damp, is what I am lead to believe. I totally understand your goals to avoid the modern stuff, but you must remember most of us in the building game were only taught at college and on the job about the modern materials. The pre-second world war techniques are really specialist now a days.

  3. I am enjoying your blog. Thanks for sharing your experience.

  4. Ahhh, nice one. It certainly sounds like it could be. I might drop them a line with a photo (the current versions are nothing like the stuff we removed) to see a) if it is, and b) if it can be dated. For no other reason than 'just to know'.
    Thanks for the message :)


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