Monday, 10 May 2010

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.


Rupert Wolfe Murray said...


Anonymous said...

Great blog. I just happened to find it linked from and will read more if it over the next few evenings.
We are rejuvenating a quinta in central Portugal, near Fundao.
Wishing you and your team strength and lots of fun,

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