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Thursday, 9 December 2010

Pot holing

I do do some silly things.  For some things that end up being silly, the thinking on it started nano seconds before, and some have had hours of thinking time and months of planning, but still end up silly.

My pot-holing experience is definitely in the latter category.  Much research was done, interstitial moisture control, permeable membranes, thermal coefficients and getting my head round the building principles at the turn of the century have all had to be mastered in pursuit of my dream.  This dream involves insulating my downstairs floor.  It is stripped floor boards and, in my opinion, absolutely beautiful, however it does have one flaw.  The suspended floor includes air flow from the air bricks spaced around the building just above ground level, the purpose of which is, for those yet to Google such subjects, to ensure an airflow in the space below, which ensures that moisture does not linger on any of the wooden surfaces.  Further, the end of the beams rest on a small wall a few inches from the outside wall, and their ends also stop a few inches from the outside wall, just to ensure that it is not in contact with said wall, which may, especially in a solid wall building, present a certain level of moisture to the inside surface.  Ditto for the beam that runs parallel to the outside wall, it too is a few inches from the wall.

So, this is a well designed and simple system for maintaining structural integrity in the under floor space.  It also presents a cold draft to any crack or gap in the floor.

Any attempt to insulate must observe the basic laws on which the building was made, and this has meant some pretty specific design.  I have used lambswool insulation, which is all very eco, albeit that some people suggest that the existence of sheep is carbon negative, but I didn't go there.  The main characteristic of lambs wool is that it can absorb water and let water disperse without affecting its thermal efficiency.  Combine this with a permeable membrane and you have something that insulates and stops the drafts, but also allows moisture to move.  i.e. it won't act like a plastic bag and trap moisture, which is the devil for the wooden suspended floor.

I also need to ensure that the insulation does not bridge the gap between the outer wall and the beams.

So, that is the science.  The method of installation is where the blog title comes in.  There are a couple of ways of retro-fitting this stuff, either to lift all the boards and do it from above, or lift a couple, crawl down in to the space and do it from below.  I picked the latter option.  This meant crawling down under the floor in a space the height of the bottom of my kneecap, lying on my back to lift in insulation, then fix it in place with a sheet of permeable membrane.  Dust?  Never seen anything like it, and the whole downstairs was covered in a thin layer.

The space is basically split in to four quadrants.  There is a wall which would have supported the wall between the two rooms (long since knocked in to one), and there is also a wall that runs front to back that supports the beams half way across.  This is half way across the whole space, which includes the hallway, so appears to be off-centre for the room itself.  I did quadrant one on Friday night.  I started on quadrant two Saturday morning, but as I exposed and inspected the space, I noticed that the wall between the rooms stops at the doorway, which means that there is a hall-width space in the wall which enables me to get to quadrant three also.  This makes me happy and sad.  Happy because I can do two quadrants with one lift of boards, but sad because it really is a long way to crawl, probably five metres or so, and for a man who is very slightly claustrophobic, a bit daunting.  Nevertheless, I have finished quadrant two and three, and just need to do quadrant four, probably Friday evening.
I also need to revisit the other quadrants because I have made one mistake in my planning.  At the ends of the beam runs, I had imagined the insulation would have blocked the draft, but in fact it is still getting through, which means that the thermal efficiency is being severely impacted - moving air is not good for insulation.  So I am intending to experiment with a small square put on the end of each run, to effectively make the insulation and membrane installation an air-tight lump on the underside of the boards, but not touching the outside wall in any way.  Don't get me wrong, the room is much warming as a result of what I have done, but unfortunately the fact there is air movement will bug me for ever more, so assuming my plan works, I will need to retrofit it to the quadrants already done, since a couple of hours doing that saves years of "what if" nagging thoughts.

Other than that, I am off to the back man today, my first visit, to see if he can do anything about my various back issues.  He comes highly recommended by a friend who works at the hospital, and lots from the hospital use him, so that sounds like an endorsement to me.

Have a good weekend, and I promise not to mention insulation again.  Probably.

1 comment:

a bad man said...

Scobi, as a fellow claustrophobe may I suggest to take the approach that the original builders would have and exploit a small child to apply the insulation. Otherwise, what was the point of having them? Cheers - Badman