Vermiculite!! Which type and where to get it???

[dougclay]

I decided to Retro-Refit-Refrub my oven by replacing the brick/builders sand under my floor with something more insulating...
Vermiculite seems to be popular, but I guess people are not using the stuff from the garden centre...
I've made a start an weather permitting I'd like to puit this in tomorrow.

What grade of vermiculite is better? fine, medium, course?
Should it be "building" vermiculite rather than horticultural type? or is it all the same?
Where can I buy some on a sunday morning?

Cheers

DougClay

[tonyb]

As far as I am aware, all vermiculite is the same. Coarse size is preferred because it should trap more air. I think I got mine from the local Jewson builder's merchant but could have been one of the other large builders supplies companies. You should be able to get it for about £11 per 100 litres from Jewson whereas garden centres only stock 5 or 10 litre bags wat about £5 a bag.

[turkey]

Near me I know Travis Perkins stocks it, I suspect most builders merchants stock it if you call round.

[dougclay]

Thanks tonyb...

I was hoping to get some to do this tomorrow, the garden centre sells fine stuff for the garden and course vermiculite to put on the floor of reptile cages... but as you say, it's smaller bags and the price is relatively quite high....

Jewsons is 5 minutes walk from my house but but their opening hours (just like the travis perkins down the road) are incompatible with my last minute approach to these things :-)
I'll have to look for Jewsons close to where I work on Monday and hope for some dry evenings...

What are opinions on the best mix? I've read about people using between 4:1 and 15:1 with cement. Does it shrink much?
I imagine something like chocolate rice crispy cakes, ie not too much chocolate ;-)

[turkey]

you got it, vermiculite is insulating concrete is not, so whilst you need some to bind it, the finer dusting of cement you can manage the better. You want it under the floor and it will be enclosed so you should be looking at 8:1 I would think.

some folks have posted their tips to make it easier, most say soak the vermiculite first and dust / mix it in a large tub or wheelbarrow.

good luck on the hunt, if you cannot find some you can always look for thermalite arrested concrete blocks, these are easily cut and good at insulating., this is what I have under my oven, although I have yet to prove it, it has been used I'm many ovens now in the UK and works ok.

[tonyb]

Generally considered that the higher the ratio the better from an insulation perspective but its more difficult to mix and apply. I think mine was 5:1 and ratios around that seem the most common. I haven't noticed any significant shrinkage.

[dougclay]

Got the Jewson lot.. :-) 1x100L bag of grade 4 Vermiculite £10.79...
I'd never seen a Jewson near my work, so was surprised to find one on the website, drove around for 40 mins trying to find it off the postcode before I gave up and went back to work... That's when I saw the Jewson which until last week was a paving warehouse.... d'oh...
I drive passed that place every day and never noticed it had changed!!

Was thinking of getting a couple of bags until I saw the size of them... I think 1 will do it for now...

I will try with an 8:1 layer tomorrow evening and see how that turns out, and then do the same all the way up or try more towards 5:1... mostly I'm just filling the void, but I'm wondering how difficult it will actually be to bring this up to the existing level under the floor bricks that I couldn't remove.. I'll need to somehow level it off, without compacting it too much...

I just realised I've had this cement for almost a year now, how long does it keep after opening? If it is still powder is it still good?

Thanks for the vermicu-tips...

Cheers

dougclay

[turkey]

cement does go off, Terry might know specifics but perhaps knock up a test fish cake sized lump of vermiculite and cement and see how it cures overnight, its going under the floor so only need to take the bricks weight.

[dougclay]

Hi Turkey, good idea, just knocked up a batch... I'll see how it looks tomorrow... weird stuff, even weirder when mixed with cement. I almost expected it to get soggy and limp when it got wet due to it's resemblence to rice cakes ;-) Is vermiculite usually silver and gold? or is it just the Silvaperl variant I got?

It's been a year since I got the cement, but I used in the winter to cement in a post. It does seem a little grittier than I remember, but its been in the paper sack inside another plastic sack in the shed... let's see... at least I know where Jewson is now for a lunchtime visit ;-)

[tonyb]

From memory, the vermiculite I used was golden/brownish with some reflective bits, though memory not as good as it was perlite is white

[dougclay]

I have filled in the under floor, looks like the cement was still OK. Filled the bottom few inches with loose Vermicuite and topped it with "vermicrete" mix 8:1:1 Vermi/Cement/Water
Did the Vermicrete in a few small batches trying different mixing techniques, with the most effective being adding the water and vermiculite first, then sprinkling a most of the cement and mixing, sprinkling a bit more and mixing, etc...
I sieved the vermiculite as there was a lot of fine particles in the bag and I found that the fine stuff turned into porridge when wet. After sieving it was much easier with the big chunks...
The fine stuff was dusted on top the next day to get the floor bricks level... not as easy as it was with dry sand, but worked out.. The rest of the fine vermiculite went in the compost...
Still got half a 100L bag but using it to loose fill the gap between arch and inner dome and will use it to insulate the chimney...

[cannyfradock]

Hello Doug

....another post that I missed, but nice to see you had some answers from the guys on board.

It sounds like you are well on your way in your re-fit.

All the best and keep us informed.

Terry