light clay straw.

[formerly known as]

we are renovating a property in the east Anglian region that contains several forms and phases of construction, the oldest being timber frame. The timber frame had been 'faced' in the mid c20th with boe and s+c render to visually correct a lean caused by roof spread - this lean corresponded with an inward deformation of the sole plate. Whilst w+d remained in places, the framed required stud renewal/s, so the w+d had to be removed; I was also keen to introduce a lighter insulation between the original timber frame and a secondary inner timber frame that I have installed so the original frame can 'hang' from it for additional support. After research, I came down on the side of hemp batts for insulation, although the cost of which was making my teeth hurt. So, enter stage left - light clay straw. LCS is basically barley straw coated in clay slip - although we added non hydraulic lime also - the slip being our own reinterpretation of 10pts water, 4pts reconstituted clay from the daub and 2pts lime, all mixed up in a water butt with a paddle mixer. The mixture is then lightly rammed between shutters and then rendered or boarded over. We will be l+p internally, with sweet chestnut feather edge outside. Have a google of light clay straw. Originating in Germany, used latterly and currently in various parts of the world and with a couple of experimental buildings in the uk. with the materials being cheap as chips, this in my opinion is a realistic alternative for an insulative panel infil. Oh, if you try it, wear long indestructible gloves to avoid scratchy straw lime burn :shock:

 

[worms]

Interesting. I once played around with wheat straw mixed with limewash, without any great success and didn't persevere.

 

[Penners]

Sounds interesting FKA, but have you done any research into the R-value of light clay straw, as compared with an equivalent thickness of other insulation materials? On the basis of no knowledge whatsoever, other than your description of the material, I find it difficult to imagine that will be as effective as - say - hemp, wool, rockwool, etc.

 

[formerly known as]

Worms - The clay and lime mix works well as a slip to bind the straw, to the extent that the shuttering can be removed by the next day. the only drawback it seems is the drying time, which is supposed to be equal to 25mm per week.

Penners - the use of this method has been driven by issues of material cost and potential longevity. I have looked into the alternatives (hempcrete/thermafleece/hempfleece/etc/etc) and it would appear that this method has an established use and success rate and is in my opinion more permeable than hempcrete that relies on hydraulic lime. The R value is good - I will have to 're-find' that info and post it up after a re google. Also, given the complexity of the structure (historic outer frame 'hanging' off a newly installed inner structural frame) ramming and shuttering an infill into complicated spaces has ensured that there will be no holes - it would have been difficult to achieve this will fleece.

It is intended that the infill is meshed then rendered with a straw lime render for consolidation before battening off and cladding in sweet chestnut feather edge.

This property is a 'keeper' so I don't mind the labour intensity.

 

[formerly known as]

http://www.designcoalition.org/articles/Natural_LHJ/liteclay.htm

R-19.

 

[Penners]

Thanks for the response, FKA. You've clearly researched the whole question so thoroughly that one could believe you are an expert.

 

[formerly known as]

Thanks for the response, FKA. You've clearly researched the whole question so thoroughly that one could believe you are an expert.

Thanks Penners ......... 'LCS Specialist' etc, would look splendid on the side of my van :wink:

 

[Penners]

'By Appointment...' of course!