Making lime putty for building

Guest post by Paulo

(edits where I couldn't resist:)

Today a truck full of bags of quicklime arrived at Casa Felix and we began the process of filling our lime pit to make lime putty. We will use this yoghurt-type stuff to make plaster in a couple of months when (notice I said when not if) the strawbale walls are completed.

For now it needs to be mixed with water and “slaked”. This is where quicklime and water meet, and will bubble and boil and get really hot, and then mellow out. This is where ye old English drinking phrase to 'slake your thirst' comes from. Many of you

who have been to the UK will at some point probably have had a pint or two at an English pub called “The Lime Kiln” – there are hundreds scattered across the country, mainly because every town used to have one as lime was essential for building before cement came along (and ruined everything). And after mixing lime, you really feel like a drink!So what's going on here? Perhaps a quick chemistry lesson is in order.

First eucalyptus roof goes up

This is the old distillery - the alambique. Jamie thinks it burned down after a heavy drinking session, evidenced by the charred tiles and debris we discovered when clearing it out. Or maybe it was the trail of empties that meander over the land, outwards from the distillery, where the local spirits were concocted.

The point is, it's a ruin, a fine ruin at that: complete dry stane structure (no mortar), deftly integrated to the bedrock protruding along the hillside.

After the Romanians, Galegos and English cleared innumerable tonnes of earth during our Mega May workfest we decided it was time to think about the roof. Manuel has worked with locally grown eucalyptus for over 30 years. He's the only one I have found around this area who is willing to work with this imported species. (Clearly eucalyptus is a problem from many points of view, something I need to research more and write about later, but I like the idea of taking it out of the hillsides, using it in our buildings, planting in native oaks and chestnut in its place).

These are massive beams: 30x20cm x 6m length. The wood is still green / wet, so it's mighty heavy. We moved it onto the land between six of us, with metal bars and ropes and lots of groaning. Nikita managed to avoid this toiling using school as an excuse... shows the scale of pieces.

A temporary stucture was built on scaffolding in the building and the beams manouvered into place. Amazing. Within half an hour these monsteres were fitted in place. Don't worry about the collapsing walls around them, Manuel assured me, you deal with that later...

A day later the whole structure was up: beams, rafters, tile battens, v-lux window from Edinburgh we'd freecycled before we left.





When we first arrived in 2008 it was almost engulfed in brambles, see left.

Monica getting physical with the brambles (before we encountered the strimmer / technosyth)

Kira and the remains of the distillery, and granite posts for pigs and vines and drunks.

Before tiles go on we had to bring the walls up to meet the roof, so Petrush and Ilie (Team Romania) used whatever stone we could find and some hydraulic lime mortar they are good at mixing to get 'er done.















Petrush mastering his rocky skills (OK I put in a rock or two there too!). West wall, before and after.




















We hope to move into this place over the summer, while we're working on the main house; I'll need to point the walls with lime to keep wind and rain out and possible internal plaster for warmth. I think we're going to build a mezzanine floor to sleep up and leave junk down. A sink, a stove, a desk, a sofa. The front wall we'll build from timber and straw and clay. Mary and John gave us windows for each side of a door. An extension out front will create a porch area, summer sleeping pad. All for the future....

House build begins with Stone and Hydraulic lime

Planning permission finally arrived early May. First off we need to take the adega wall down, insert foundation stones, get it square (full 90 degrees) to the main house (so the roof of both buildings fit together properly). João our stonemason was actually the one to point all this out (architect and engineer didn't seem to notice). Here he is, left, with his new toy doing his thing!

Day1: Wall comes down in bits. João stashes the main big stones strategically, then digs ditch for the foundation stones. No cement foundations here - pedras de Porinno (vast granite lumps, from about 30km away).








Day2. Re-align wall so that it sits at a proper right angle to the main house. Tools used: some string and a bit of right angled metal. Foundation blocks in.



Day 3. Wall starts to go up; first 70cm or so. Site for door chosen. First mixes of hydraulic lime (full strength: NHL5. This stands for natural hydraulic lime by the way. It's not actually pure lime, it has a bunch of clay impurities in it, or baked clay basically. Which means we don't need to add pozzolans. Hmmm, lime needs more discussion than this. Soon).



Day 4. More wall goes up. New window bearer chosen (chunk of granite that the window frame will sit on). Lime mortar going off nicely within 24 hours. Sand - lime mix used was more or less 2.5 sand to 1 lime. Nada mais.














These slabs are the foundation stones. João put them in that trench he had dug and that was that. No faffing with cement foundations and all that.


João thinking. About this window. Used to be a door there. And steps will go on the other side. So it can't be too low. Nor too high...















By day 6 João realised we should maybe have taken out all the rubble from inside first... uh oh. No problem he exlaims, we'll dig it out through the doorway. Within 20cm or so we found nothing but bedrock, so we hired a compressor and drilling thing and hammered away for another 4 or 5 days. Slow, grinding work.















Conrad and his Pa Jon (and daughter Lula) visited during all this, and Jon muscled in there with the rest of them - at 70 and still as strong as the next guy!

So up until today we've been digging down: to around 30cm below eventual floor level so we can fit in all that underfloor stuff. And now we have to learn all about floors - and if we want to avoid cement and plastic (DPC) we have to think carefully. So far we're thinking thus: 1. 8cm small river stones for drainage and capilliary break (so water can't come up). Some kind of geotextile that prevents moisture - if it's somehow made it up past the stones - but allows floor to "breathe". 3. Insulation, maybe cork, maybe 6 to 8cm. 4. Limecrete floor with underfloor heating at about 7cm. 5 final cover, lime and broken tiles, like in Roman times. Which sounds good in the Lime Book.















These photos show how much rock we have to get through...


Mainly, we've been learning about hydraulic lime mortars: how they work, how they don't. We've found the best mix when you mix water and lime first, for 5 mins or so, then add the sand, slowly, and water bit by bit till you get the right consistency.