Sheep Wool between joists under floor

new_owner

Hello

I have moved into a victorian (1880) terrace house.

The house is somewhat drafty and cold

I have exposed boards in the dinning room which I am planning to sand down and oil.

I have filled the gaps with a roll of thin foam tube, which has stopped the drafts coming up (Previously filled by another owner with pva glue and sawdust but was falling out)

I have been thinking about insulating under the floor (Just finished the loft, never want to see a roll of Rockwool again ) and wondered if there was any issue with using sheep's wool as it should allow the floor air to still move?

Under the dinning room is a heated cellar which has an air brick and another air brick for the joists.

I was thinking about a wire mesh stapled to the joists with sheep's wool on top up to the depth of the floorboards...

There is no damp in the wood as its well ventilated and I am concerned that stuffing in insulation might introduce damp or other problems.

I have browsed the net and this seems to be the way to go.. But most people seem to have an unheated cellar or void.

Access is easy as I can do this from bellow.

Any recommendations?

Thank you

keyfob

I can't see any problems with doing what you've suggested, but al;so I really see what the benefit would be.

You be far better off insulating the outside walls, which you would probably have to do on the inside surface. The best way however would be to insulate on the outside surface and there are a number of proprietary methods for doing this.

mart.vader

http://uk.sheepwoolinsulation.com/why_wool/homeowner.asp

27col

I am not sure what you mean when you say that using sheep's wool "should allow the floor air to move". The whole point of any insulation is to provide a blanket of still air. Moving air does not provide any insulation.
I doubt whether using sheep's wool would be any easier to install. Using string stapled to the underside of the joist will keep most types of insulation in place without the need for wire mesh.

new_owner

Thank you for your replies..

keyfob wrote: »

I can't see any problems with doing what you've suggested, but al;so I really see what the benefit would be.

You be far better off insulating the outside walls, which you would probably have to do on the inside surface. The best way however would be to insulate on the outside surface and there are a number of proprietary methods for doing this.

I had read that almost as much heat is lost through the floor as through the loft for a raised timber floor..

I have looked at insulating the outside walls but the cost is very high. The trouble with doing the inside walls is loss of space and again cost vs gain. So loft has been done as there was almost no insulation in the loft.

27col wrote:

I am not sure what you mean when you say that using sheep's wool "should allow the floor air to move". The whole point of any insulation is to provide a blanket of still air. Moving air does not provide any insulation."

Sorry "breath" was really what I was supposed to say without restricting what the air flow was designed to do...prevent damp

new_owner

just found this interesting article by the English Heritage.

helm.org.uk/upload/pdf/eehb-insulation-suspended-floors.pdf

A quote from it "In many cases it may even be possible to achieve the full target U-value of 0.25W/m2K set out in the 2006 Building Regulations simply by installing insulation between the joists. Individual calculations will need to be carried out for each situation, and will usually be provided free of charge by material suppliers, but it is quite possible for as little as 150mm of sheep’s wool insulation to meet the required standard for new buildings, assuming air infiltration rates are well controlled by allied methods. Greater depths of insulation can usefully be installed, but very large quantities may actually not be cost effective."

So guess what I am doing on Monday

Thank you for your help

Biggles

Why do you want to insulate one heated room from another heated room? Where is the gain?

new_owner

Biggles wrote: »

Why do you want to insulate one heated room from another heated room? Where is the gain?

The cellar has a radiator, which works but is not warm...

The central heating is OK... but the whole bottom of the house will be cold 30 mins after its off... There are just to many drafts coming up through floor from the colder rooms and through the air bricks.

So to save me having to have the CH on all the time to fight the cooling affect the more sensible idea was to insulate and remove the drafts.

I am having a wood burner fitted in a couple of weeks which will get rid of the open fire and stop most of the heat rushing up the chimney. But it would be nicer for the house to be a little warmer....and keep the heat for a while

The open fire has been a god send and has kept us warm over winter and after reading about the benefits of a wood burner over an open fire we decided to get one fitted.

Reading up on this it seems that it will be the best thing to do on the ground floor is insulate under all the floors...

But back to your question... As I am tempted to carry this through the entire house...

Would in not make sense to insulate between all the floors to keep the heat in the room? each room has a radiator (nearly the right size, but that will be fixed in the summer) the best place for that radiators heat is to stay in the room its in and not drift into another above or bellow?

t_obermory

I have a house of a similar age and briefly looked into insulating under the floorboards before discarding the idea as being more hassle than what its worth. The air vents are there to stop damp appearing (something I know from personal experience) and when I looked into it seems that you're not supposed to insulate up to/over the joists in order to prevent the boards from getting damp. One of my rooms has had the wooden joists removed and has a concrete floor which is much warmer than the room with the vents though obviously that wouldn't work over the cellar! However the easiest method I found of retaining the heat is to have wool underlay and a good quality carpet, the difference between that and just sanded boards is unbelievable. Boards do look lovely but compared to carpet they are always going to be colder.

fluffpot

Beware sheep's wool! A client of mine had to have the WHOLE house re-insulated, re-plaster boarded, plastered and decorated because of a moth problem - they came from the sheep's wool used in all walls as eco insulation....

new_owner

t_obermory wrote: »

I have a house of a similar age and briefly looked into insulating under the floorboards before discarding the idea as being more hassle than what its worth. The air vents are there to stop damp appearing (something I know from personal experience) and when I looked into it seems that you're not supposed to insulate up to/over the joists in order to prevent the boards from getting damp. One of my rooms has had the wooden joists removed and has a concrete floor which is much warmer than the room with the vents though obviously that wouldn't work over the cellar! However the easiest method I found of retaining the heat is to have wool underlay and a good quality carpet, the difference between that and just sanded boards is unbelievable. Boards do look lovely but compared to carpet they are always going to be colder.

Thank you for your reply

Its going to be a huge amount of hassle to insulate under all the boards (bar doing it from the cellar). From what I have read about insulating older houses, wool insulation seems to be OK in regards to damp (hygroscopic) as long as you don't block the air vent and allow air to circulate under the joists. I think I will use chicken wire, or something along that line, stapled to the joists and insulate up to the boards. I will seal between the boards to prevent liquid accidentally being spilt between boards and ending up in the insulation.

It seems that just as much heat can be lost from the floor as through the loft, and since I have no intention of replacing the single glazed sash windows (another major heat loss) it will help minimize loss compared to where we currently are.

I have factored in the cost of replacing the odd board that might get broken, with a reclaimed one, when I have to pull them up (and a couple that need replacing now)... I don't think to do the whole house the the cost is going to that high vs gain in warmth and reduced heating cost.

+ it gives me the chance to put better radiators in (a more traditional style and more in keeping with the house, than the current ones)... and check the electrics (move a couple of sockets).

The plan is to expose the boards through out the house and use some good size rugs in the bedrooms as more or a decrative feature.

I guess time will tell (well next year ) as to whether it was worth the effort.