It wasn’t planned but the house is to get well over 10 types of plaster finishes /dry lining boards during the refurb. Much of them are DIY so lots of new skills to learn and tools to buy.
First, I must start with two materials that are a long way from green. The first is gypsum plasterboard (1), put up quickly by my amazing dad when a new partition was needed at the start, and before being brave enough to think we could do this stuff ourselves. Annoying material plasterboard – non recyclable and made of mined and mixed virgin material. It is however cheap, easy to put up and a staple of British house building. A gypsum plaster skim (2) will have to cover it as it won’t take much else, will borrow my brother to help with this*.
Clay board (3) is next, a bit of an impulse purchase picked up (from Back to Earth) en route to friends in Devon a year ago. It’s going in the understairs cubby loo, very good sound proofing apparently. It’s a bit crumbly but feels like it must be good and looking forward to having a go with it. Clay plaster (4) will cover it, very heavy stuff. Apparently it’s easy to work with and you can mold sculptures as you go, if you’re that way inclined.
Gypsum fibreboard (5) (Femacell) is a new find (though around for 40 years+) and introduced to me by Tim, our friendly contractor at Ecovert Solutions. It’s made from “recycled gypsum [waste product from a power station], cellulose fibres from post consumer waste paper and water, no added chemicals. All by-products and off cuts are fed back into the production cycle“. Sadly, the plant is in Holland so getting the bits back for recovery is a little impractical (why is Britain not really into this kind of thing?
groan). It’s a nice material, reassuringly heavy and smooth. It was interesting balancing it on my head as the bathroom ceiling ever-so slowly took shape. A home made prop made it a slightly less painful experience. What a joy to have a ceiling, the pleasures in life. Fine surface treatment (6) will be applied after filling the holes, simply scraped on apparently. I’m assured that this is a doddle, we shall see. Interestingly one of the builders tells me this is the approach used typically in France where he comes from, rather than the gypsum plaster here. I haven’t managed to work out what its eco credentials are yet or if it has any but at least you don’t need much of it.
Hydraulic lime mortar NHL5 (7) has been used to pointing of the foundation brickwork below the damp proof course. Two gullies with years of overflow and a leak or two was the cause. This was a new foray into the world of lime and it was piece of cake. Well, it was less difficult than imagined and I’ve leaned that the higher the NHL number the less breathable, the quicker it sets and the harder it is – NHL5 is good in wetter situations like foundations. Hemp with lime putty (8) came out the blue. A lime plastering course at Ty Mawr in the beautiful Breccon Beacons led to a ‘let’s pull down the dodgy 80’s stipple, plasterboard and everything else on the kitchen ceiling** and start again’ thought. And we did. The original lathe (wooden strips), almost perfect bar mice nibbles and missing bits, were left in situ and patched up and covered with this stuff. Bit of
a trial first time around, to prepare, ‘knock up’, put on (as plasterer’s mate, it was hard enough) and to keep it up there. It looks pretty darn good (to me). It takes a month to dry apparently and demands a cooler environment and lots of ventilation. Given that there is currently no heating in half the house (removed in a moment of controlled madness) and still gaps the size of the cat around
windows, these needs are easily met. Hydraulic lime mortar NHL 3.5 (9) is plugging all the gaps inside, including unused waste pipe holes, between bricks, dips in walls etc. Tim tells me ‘you can use sand and lime to do pretty much anything‘ so we are and so is he.
So, what’s so good about lime? A summary of +’s from GreenSpec…produced at lower temperatures so needs less energy and therefore generates lower CO2 emissions; lime putty absorbs nearly its own weight in CO2 in the curing process and hydraulic lime around 75%; lime mortar can be re-cycled unlike cement; bricks using lime mortar can be reused/recycled unlike the cement bonded equivalent which can only be used for hardcore; buildings built using lime mortar move and absorb moisture. In comparison with cement mortar which is rigid, lime mortar ‘moves’ with the structure and so prevents masonry from cracking.
Sand with lime putty (coarse) (10) ready made from Ty Mawr for the base coats of walls in the bathroom has worked better than expected though the plaster seemed to take an age to knock up. This situation was improved somewhat by our contractor providing a little advice
and his twin handled mixer (much appreciated). The tool wrenched arms much less than the inferior version attached to the drill, and would certainly make a more accomplished giant cake. It was critical to drench the walls with water beforehand otherwise the red brick would sucks all the moisture out and turn the plaster to dust or so we’re told. Other walls in the kitchen and elsewhere will also get this treatment. Sand and lime putty (fine) (11) will provide the final smooth coat although I am somewhat skeptical at our chances of getting a fine glass like and flat finish and will aim lower so as not to be disappointed, overrated anyway. Clay paint (12) will hide a multitude of sins. Secil’s
Adherevit ecocork (13) from Mike Wye is hydraulic lime with cork and sticks the 200mm cork boards (14) on the main part of the wall to form the external wall insulation (EWI). Expandable Styropor boards (15), below the damp proof course, and Pavaflex wood fibre board are also in place and along with the cork will be rendered with the ecocork, which also makes up the two principle base coats of the main render. Secil Finishing Render (16) made up of hydraulic lime with calcium and other minerals, provides a breathable skin before Baumit’s Nanopor paint (17) is brushed on. Apparently it’s self-cleaning and breathable – the manufacturers are almost evangelical about it in their brochure.
There are so many more interesting materials and, as another of the builders tells me as parcels arrive on the doorstep, ‘it’s like Christmas every day ‘, and it is.
*Just been told that I can use another finish DG27 (18) to prime the board so lime can be applied, great – thanks Franck!
** There will be more ceilings to sort and another tip from Franck is to use the lighter wood wool (19) – I’ve seen a sample and would love to have a go with it!