Questions You Should Know about Vermiculite Insulated Pipe Holder

Having said the above I have fitted plenty of liners in huge chimneys in exposed locations (top of Welsh mountains) and never had a problem.

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Otherwise it is not necessary, especially if the majority of the chimney is internal within the building. The air between the liner and the chimney wall will insulate the liner (air is a good insulator) although the liner obviously touches a cold wall in many places. Adding a blanket wrap makes a reasonably stressful job super stressful if not impossible (unless the chimney is without doubt of sufficient size to cope). Adding Vermiculite or Micafill can cause damp problems (don't do it).

Vermiculite or Micafill when insulating a liner?

Vermiculite or Micafill: I have my reservations about these methods. This stuff absorbs and retains water so if your chimney leaks water at all the insulation material will gradually get wetter, absorbing like a sponge. This can promote damp walls in rooms that previously were problem free.

Update 26 Sept

I am a member of an installers forum. A recent discussion on the forum was 95% in favour of NEVER using poured insulation in a chimney. Lots of installers have had problems with damp.

Blanket type wrap is fine albeit very heavy making fitting very difficult.

There is NO Building Regulation that says you must insulate a liner. However regulations do state that gases must be safely taken away from the building so in theory a stove could be tested on site and could fail this hurdle if the draw of the chimney does not reach the figure stipulated by the stove manufacturer (it is possible to test chimney draw but from my limited experience in these matters a chimney would not fail this test if a liner is fitted, with or without insulation).

Update Monday 24th February

I have just had a long chat with the Hetas Technical helpline regarding lining and insulating. I was prompted to call the helpline following a call from a fellow Hetas engineer (in his first two years on the job) who had received advice that he was unsure about (unsure only because the subject had not been covered in his training course).

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The Hetas engineer had been informed by a Hetas inspector that he should always conduct a full “smoke test 1” (smoke test one) on a chimney prior to installing a liner and granular insulation. This is not something I have done in the past and so I was surprised.

The Hetas Technical Helpline said that this was information that can be found in a British Standard and was now being promoted, as good practice, by Hetas. The reason for this was a number of instances where Hetas engineers had filled chimneys with granular insulation only to find out that it poured into next door’s fireplace due to gaps in the “feathers” (wall between tow flues), three instances over Christmas I believe. I was told that Hetas engineers would soon receive an update about this.

Granular insulation – consider it but do you really need it? In my own home I would generally not bother unless the flue was massive – and then I would use Chimwrap. Talking to a few other Hetas engineers reveals that over 95% of installs are completed without any insulation and one engineer I know refuses to add granules due to the possibility of dampness getting into the insulation.

Back to smoke testing before adding the liner. I can see the sense of smoke testing if granules are to be added. It would be bad news to find granules pouring into next door’s house (especially if mixed with soot and ending on a beige carpet).

Smoke tests with party walls can be difficult – both parties have to agree and both houses accessed during the test. I was advised by Hetas to read The Party Wall Act and will do so shortly (fun).

The second item raised by the Hetas installer was that the inspector told him that he should always mix his granular insulation with mortar (6:1 granules to mortar). My reaction to this is one of horror as I believe that if you were to do this then you never be able to retrieve that liner from the chimney. I asked the chap on the Hetas Technical Helpline about this and he said that he would never advise to add mortar for the very same reason (so conflicting advice). Many articles on the Internet say to add mortar but I would never do this to my own chimney (or anybody elses) and have never done this.

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staceyneil

New Member

Feb 25,

12

Coastal Maine

• Oct 16,

• #1

I have another thread about our chimney lining/insulation project but thought I'd post this specific question here in case others are looking for the answer, too

We're lining an interior masonry chimney with SS liner (not technically necessary but we're doing it anyway.) We do not NEED to insulate the chimney, but plan to use Kaowool at the bottom block off plate and also stuff some down the top of the chimney as far as we can reach.

We're considering also filling the rest of the chimney with Perlite of Vermiculite. I have found several types, sizes, and grades. A local masonry supply place sells VERY FINE perlite for filling masonry walls. I would rather use a coarser material that's less likely to sift through teeny gaps we might miss.... the horticultural type -for seed-starting- is much coarser, and also easier to get locally. Is it safe to use that stuff?

Thank you!
Stacey

laynes69

Minister of Fire

Oct 2,

2,677

Ashland OH

• Oct 16,

• #2

Its all fireproof. I used the course that I got through the local concrete supply. I think it could be used in gardening for ours isn't treated for water. If the chimney is in good shape along with the liner, there shouldn't be any worries for moisture. If your worried about moisture retention, go with perlite.

branchburner

Minister of Fire

Sep 27,

2,758

southern NH

• Oct 16,

• #3

laynes69 said: If your worried about moisture retention, go with perlite.

Or else make sure the vermiculite has been treated with silicon for water resistance. Treated = construction grade, non-treated = horticultural grade. If there is concern about it sifting through any cracks, I think you are wise to go with the coarser material. And even if there is little chance of water penetration, I also think it is wise to use a material that will not expand with moisture.

oconnor

Minister of Fire

Nov 20,

1,074

Nova Scotia

• Oct 16,

• #4

Stacey

I may have mentioned this in your other thread before, but it merits repeating. Make sure you use the material that your liner manufacturer states is appropriate for their product. You are playing with fire here, literally, so it's really worth playing by the rules. There are lots of places in life worth taking shortcuts to save money, but chimney liner installations aren't one of them.

You mention that you don't need to insulate, so I assume that means you discovered that your chimney has 2 inches of air gap around it all the way up. If you do have that, then there is no need to insulate for performance with an interior chimney.

So why are you insulating?

staceyneil

New Member

Feb 25,

12

Coastal Maine

• Oct 17,

• #5

Thanks, guys...
Brent, We just figured it might help the stove draw better and decrease creosote build-up, especially at the top where the masonry chimney runs outside the house.....
The sweep who was here the other day said he wouldn't insulate at all, but then again he also said he didn't see anything wrong with just sticking a short piece of liner up through the flue and calling that good...
We're now leaning towards just insulating the block off plate at the bottom, and stuffing some kaowool down as far as we can from the top.
Thanks-
Stacey