Hemp insulation

sculptor · 10-03-2008 12:54pm #1

Has anyone used or have opinions on hemp insulation for dry lining?
Or hemp plaster?

lastbuilders · 10-03-2008 2:23pm

I used it in my timber frame selfbuild and am very happy with it. My brothers and I had many long hours putting it into every space we could. A bit of a chore but worth it in the end. It is not irritating to touch and use so we didn't need any protevctive equipment which helped.

House is 2700 sq ft and heating and hot water (wood pellet boiler) last year was about 600 euros which I think is quite good. Also have HRV and got house very airtight during construction which I think is equally as important as the type of insulation.

Lastbuilders

sculptor · 10-03-2008 3:58pm

What depth did you use.

lastbuilders · 10-03-2008 8:03pm

190mm in external walls and 220 in attic.

Lastbuilders

Builderfromhell · 10-03-2008 9:12pm

I am also very interested in Hemp insulation for it's Hydroscopic (hope I spelt taht right) qualities.
Could you tell us ;
1. How does price compare to say Rockwool ?
2. Where can it be sourced ?

lastbuilders · 11-03-2008 1:54pm

I didn't price against rockwool but it is a good bit more expensive than fiberglass.
I got mine from ecological building systems in Athboy.

Just to also add that I know someone who works for the company as well as being a satisfied customer as per posting guidelines.

Lastbuilders

11-03-2008 5:38pm

Builderfromhell wrote: »

(hope I spelt taht right)

that

*

*sorry couldn't resist it!

sinnerboy · 11-03-2008 6:11pm

hygroscopic

couln'r resit taht :pac:

Mellor · 11-03-2008 6:17pm

sinnerboy wrote: »

hygroscopic

couln'r resit taht :pac:

Yeah, sinner is right on spelling, but don't worry, its never spelt correctly.
I mean I have seen it spelt wrong maybe 15 times here, but only once correctly.
Hydroscopic is still a word, just nothing to do with insulation

sculptor · 12-03-2008 3:59pm

190mm is a lot off my little extension.
Has anyone got any other hygrostatic solutions. ?
Is a solution hygrostatic?;)

Builderfromhell · 12-03-2008 4:40pm

Appreciate the Spelling lesson boys & girls. As a builder I only need good English when it comes to saying things like ;
'I didn't price for that, that'll be extra.'
'That wasn't on the drawings (or on spec.).
'We could have finished weeks ago but you changed your mind...' etc. etc.
'That slope in the floor is to allow flood water to escape'.

Still love to hear different opinions or experiences with hemp insulation.

lastbuilders · 13-03-2008 9:56am

190m in external walls was made up of 140mm in frame and 50mm in service cavity.

Lastbuilders

sculptor · 13-03-2008 12:04pm

How does rockwool compare with hemp, do you need less depth?
And who supplies it?
At this stage it looks like I'll follow the herd and use pu.
When I took up the old floor there was white scummy fungus under the dpm.
there wasnt any between the drylining and old brick, I hadnt put a vapour barrier there. So I'm worried that if I put pu with a vapour barrier on the walls I'll end up with fungus there.
Which is why I'm looking for something hygroscopic.

Spartacus200873 · 14-03-2008 11:46am

Hi,

I am building an extension.

I am trying to compare RockWool and Hemp for insulation.

I am finding it hard to get a price for Hemp. How much roughly would 300mm insulation on a 40sq metres extension cost (standard pitch roof)?

From a U-Value point of view is Hemp worth it?

Many thanks.

Mellor · 14-03-2008 11:49am

Spartacus200873 wrote: »

Hi,

I am building an extension.

I am trying to compare RockWool and Hemp for insulation.

I am finding it hard to get a price for Hemp. How much roughly would 300mm insulation on a 40sq metres extension cost (standard pitch roof)?

From a U-Value point of view is Hemp worth it?

Many thanks.

we had a hemp thread earlier in the week, im going to merge these two,

sydthebeat · 14-03-2008 12:10pm

Rockwool has a thermal conductivity of 0.38
Hemp can vary widely depending on type, moisture levels, humidity levels etc.
Hemps thermal conductivity can vary from 0.34-0.49 at 65% humidity.

Hemp has added advantages of being a better hygroscopic material, it also absorbs carbon, and as its a natural product theres a lot less 'embodied carbon' in its production.

sculptor · 14-03-2008 5:19pm

Thanks Mellor,
So Syd, how much hemp do I need to put inside a 230 solid wall (brick and block) behind membrane and sasamox to give me reasonable U values. Its a victorian house so I'm not expecting passive house standards.

sydthebeat · 14-03-2008 5:29pm

what thickness of sasmox???

I will assume a TC value of 0.4 for the Hemp.... (roughly half way between 0.37 and 0.45)

sydthebeat · 14-03-2008 5:33pm

230 masonry wall
25mm air gap between battens
105mm of thermo-hemp
13mm plasterboard

This make up would give you a u value of 0.27... which would be a reasonable value as it meets current minimum regulations for new builds.

sculptor · 17-03-2008 2:11pm

Thanks Syd, 143mm x 2 is a big slice out of a 3300mm room.
Do you still need the 25mm gap even though the hemp is breathable?
Sorry for all the tedious questions but the more info I have before I talk to the sales rep again.

sinnerboy · 18-03-2008 11:18pm

hemp is soft and can't be placed accross battens - must be between

better to spit 100 hemp thickness into 2 x 50mm layers

first layer between battens - horizontal
second layer between battens - vertical

FIRSTLY

apply breather membrane* to inner wall wall face - i.e. before battens and insulation

AND

use vapour check membrane* to warm side of insulation

the irish agent will for these materials* will give trade names that forum rules forbid me to post

don't sandwich cables between insulation layers

do sandwich heating pipes however - a nice detail is to have rad pipes "pop out" from wall not floor

sculptor · 19-03-2008 3:09pm

Is the supplier from the royal county and is he sound?

sinnerboy · 19-03-2008 3:27pm

yes - and seems to be . Made presentation at Homebond seminar in citywest hotel

and you can see mock up Cultivate Centre in Temple Bar

sculptor · 20-03-2008 10:05am

Thanks Syd, Nothing like an excuse to go into town for a few hours.
Not like I'm busy I have to wait another week for the steel channels to go in, thats another thing. Are steel channels a cold bridge? I will have two each side of the room should I lag them and case in composite board?

We Are Leeds · 20-03-2008 10:24am

.........

sinnerboy · 20-03-2008 11:40am

sculptor wrote: »

Thanks Syd, Nothing like an excuse to go into town for a few hours.
Not like I'm busy I have to wait another week for the steel channels to go in, thats another thing. Are steel channels a cold bridge? I will have two each side of the room should I lag them and case in composite board?

bigtime

most definatley

sculptor · 21-03-2008 10:12am

Had a look at that display, nice organic feel to it.
Next question, what happens to the moisture that penetrates the solid wall and reaches the breather membrane?
Does it trickle down and if so where does it go?
How do you fix the membrane without causing ingress and rusting your fixings?
If you take out a hilti nail thats been in a damp wall for a few years you know what I mean.
Someone tell me to shut up if I'm getting too tedious.

thinkofaname! · 24-03-2008 2:27am

Hi, have build a wood frame, hemp and lime garden room over the last year. Got my hemp and an awful lot of help from a guy in Kerry. If you want details, I can PM them to you.

Builderfromhell · 24-03-2008 2:21pm

Does Hemp insulation have an IAB cert.? If not I expect it would be difficult to get a BER cert rating. or indeed a cert of compliance.

thinkofaname! · 25-03-2008 3:05am

Builderfromhell wrote: »

Does Hemp insulation have an IAB cert.? If not I expect it would be difficult to get a BER cert rating. or indeed a cert of compliance.

Suffolk Housing Society built a couple of hemp houses, so there is a precedent, at least in the UK. That I know of, there is one new build hemp house finished in Ireland and at least two refurbishments.
There is an architect in Dublin who has spoken at a few things re hemp building. His name escapes me right now but if he is prepared to design, he should be prepared to certify.
From my experience, the problem with hemp plaster is that it is slow and weather is a big issue. But it is certainly not as toxic (speaking personally) as plasterboard and skim, although I still wear a mask and lime burns like hell!!

sas · 25-03-2008 10:00am

thinkofaname! wrote: »

There is an architect in Dublin who has spoken at a few things re hemp building. His name escapes me right now but if he is prepared to design, he should be prepared to certify.

Patrick Daly by any chance?

I don't think this discussion is about a structural Hemp wall, its about HEMP as the infill insulation in a timber frame house.

Why are people so interested in Hemp , its shockingly expensive. Cellulose to me seems a better solution. It has similar properties in terms of breathablility and thermal conductivity but you can have it pumped in for less than half the equivalent u-value of the Hemp insulated wall.

The only reason i can see Hemp as an alternative to cellulose is that its reversible in that you can take it out and put it back in again. Possibly the only other reason is that there is a potential for cellulose to compress under its own weight over time whereas Hemp allegedly doesn't sag.

Hemp insulation

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