Alternative Technology Assn Forums

1. 

   RC
   Member

   Some 15 months ago I build several main walls of my new house with Timbercrete Super Insulating blocks (600mmx175mm) single skin walls. I gave the bricklayer information pertaining to mortar mix and laying of blocks and on completion I coated the external walls with Grimes water repellent Timbercrete blend. What I have noticed when there are strong winds and rain that water is seeping through some of the mortar joins I am now very concerned that maybe the brick layer did not add sufficient Timbercrete mortar shield or he incorrectly mixed the mortar mix. I am not sure what to do and what is happening within those mortar joins. Does anyone have any suggestions to remedy the problem.

   On a positive note, the blocks work extremely well, house is very cosy in winter even without any heating (SE Australian climate).

   Cheers RC

   Posted Friday 31 Jul 2015 @ 6:43:34 am from IP #
2. 

   Annette
   Member

   Chat to the brick layer and also to the manufacturer.

   Posted Friday 31 Jul 2015 @ 9:24:29 am from IP #
3. 

   Chip
   Member

   Friends recently built with timbercrete external walls. Mortar between courses was 15 to 20mm deep and varied a bit as blocks varied in height. Advice to them was to use ironed joints (concave, dished) and they took a lot of care to get them smooth. Best tool ended up being a dessert spoon which could be angled to accommodate differences in joint thickness as the spoon was drawn along.

   Despite two coats of recommended waterproofing on the outside, there was one small spot where some water weeped in so they fixed a couple of small holes in outer surface (including a couple of tiny ones in the blocks themselves just a bit above joints). Then a further coat of finish and no problems since. To get colour right, I think that they crushed a left over block and mixed with some Bondcrete or similar clear drying glue to form a paste for patching.

   Overall they are very happy with the finished house and it looks great and feels warm.

   Posted Saturday 1 Aug 2015 @ 10:10:39 pm from IP #
4. 

   8688john
   Member

   Maybe problem is cracks due to mortar shrinkage, or failure to add waterproofing ad-mixture to mortar. You gave your bricklayer information, but did he use it?

   You need the right blend of sands to prevent mortar shrinkage. The Timbercrete manual details how to do a test panel to check for shrinkage; did he do one first, and let it dry for a week to verify before continuing??

   A waterproofing admixture such as Krystol Interface Membrane is designed to activate and grow crystals when moisture penetrates through cracks in the mortar. In theory at least the wall should repair in there are any cracks. Agree with Chip regarding concave, ironed joints. Same advice was given to me.

   I had one exposed external wall that wept slightly at some joints – but only once.

   Posted Tuesday 4 Aug 2015 @ 1:35:32 pm from IP #

RSS feed for this topic