A slight diversion from our house, to the church across the road where they are in the process of laying a limecrete floor in part the church. This is noteworthy as all too often ignorance wins and a concrete slab gets laid, or the flagstones are sealed (so why bother with a breathable floor underneath?). I found a year ago that there was very little detailed guidance on-line when researching the design of our limecrete floor, so I make no apologies for giving such detail here again.
The church architect got the design of the floor from Ty-Mawr, who are one of the main lime suppliers in this country (I used Mike Wye but there are others...). The floor design is basically the same as the one I laid in the kitchen here (see
this post last year), apart from using Recycled Foamed Glass (RFG) instead of light expanded clay aggregate (LECA). In detail, from the bottom up, there is a geotextile membrane, 200mm of (lightly compacted) loosefill aggregate of RFG, another layer of membrane, then a 3:1 mix of RFG and NHL5 to form the slab (I think, 150mm thick).
The slab has now been laid by The Limecrete Company and looks impressive (right). The edges have a vertical inch thick piece of woodwool, whose function I have yet to understand but it might be related to crack prevention. There will be underfloor heating (UFH) pipes added with a 3 inch Glaster screed and 20mm Creeton limestone tiles on top, although this heating will not be connected until a new boiler is fitted in a later phase. This work is the second stage (of about four!) of renovating the church; phase 1 was electrics, lighting, sound and internal redecoration. The next phases will also include installing toilets and a servery, and levelling the entire floor with the same sort of floor with UFH (and chairs instead of Victorian pews).
4 comments:
what are the advantages to a limecrete floor? is it possible for ground water or water from the soil to rise up and dampen the slab, or does the LECA prevent that?
A properly constructed limecrete floor allows the passage of water vapour from below so that it gets evaporated in the room rather than collecting underneath in liquid form. Water should not collect under the slab if you have made sure that the ground level outside is a few inches below the loevel of the top of the floor. (I think six inches is ideal.) You also need to make sure that the drains are working properly to take water away from the house.
Hey, do you know the origin of a limecrete floor? I am doing an assignment on traditional building techniques and my flooring system is limecrete, can't pin point the origin though. Thank you, keep on blogging - they are fantastic.
No I don't know. It's obviously a modern word but the Romans were great users of lime, so I think I would start looking there. Presumably they laid all their mosaics on a lime bed, but would you call it limecrete? The modern limecrete composition as described in the blog is a highly developed version, using LECA or RFG in the mix etc.
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