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Sempatap: DIY product to insulate sold walls

Dear all

I wanted to pass on some information about a DIY product available to internally insulate solid walls.

Last week I met with Linzi Bagshaw from Mould Growth Consultants who produce "Sempatap Thermal" - a 10mm thick foam backed "wallpaper" which can be used to reduce heat loss through external solid walls. The product is Energy Saving Trust recommended.  Rolls (12.5m x 1m) cost from £145 + £25 for adhesive and £5.70 for sealant.

Linzi would be happy to attend events or meetings to tell you more about the product:

Linzi Bagshaw 

Energy Efficiency Project Manager 

MGC 

McMillan House 

54 - 56 Cheam Common Road 

Worcester Park 

Surrey 

KT4 8RH 

Tel: 020 8337 0731 

Fax: 020 8337 3739 

Mobile: 07798 837832 

Email: linzi [dot] bagshaw [at] mgcltd [dot] co [dot] uk 

Website: www.mgcltd.co.uk

 

Jessica

Jessica Binks 

Energy Strategy Officer 

Sustainable Services Division

Environment and Housing Department

Southwark Council

Originally submitted by jessica on Tue, 11/05/2010 - 10:07am.

Last update on Wed, 12/05/2010 - 2:42pm.

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#1

Submitted by anna on Tue, 11/05/2010 - 3:16pm.

Thank you Jessica.

Sempatap has been available for many years now.  [Indeed, it was my dissatisfaction with the "sempatap solution" 6 years ago that got me really actively engaged in energy issues.]  The main problem with it is that most people don't want squishy walls - makes them feel they're living inside a padded cell - or that if the sempatap has been slightly reinforced, it isn't sufficiently sturdy to have such outlandish and rare objects as pictures, shelves etc attached to the wall.  However, it may be useful in some instances.

Presumably you do know of other producers or distributors of sempatap or similar?  We'd be very interested to receive information about them too so that, should Peckham Power decide it might be useful to have a demonstration, we are able to pursue a range of contacts rather than be passively beholden to only one.

Kind regards,

Anna

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#2

Submitted by jessica on Tue, 11/05/2010 - 3:33pm.

Hi Anna

Yes, I'm aware Sempatap has been around for a while - Southwark have fitted it for some time as a remedy to mould growth and I actually have some in my own house!

As far as I know Mould Growth Consultants are currently the only supplier of Sempatap in the UK at the moment. The only similar product I have heard of is Walltransform Warm-a-wall, which requires a skim plaster finish:

http://www.walltransform.co.uk/

Best wishes

Jessica

Jessica

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#3

Submitted by Jack on Tue, 11/05/2010 - 7:25pm.

Many thanks for this.

 

My two cents:
 
Sempatap is pretty controversial stuff.  It's an "EST recommended product" (and the 10:10 campaign have adopted the EST's recommendations).  But Sempatap gets pretty slated on the Green Building Forum (which is mostly populated by green refurbishment professionals). I've heard it said that strictly speaking, installing sempatap to an entire wall contravenes building regs because building regs require you to achieve a u-value of 0.35 if you modify more than 25% of an external wall but 10mm of Sempatap over a 9" solid wall only gets you to a u-value of 1.47 (although it's not entirely clear if gluing Sempatap to a wall qualifies as "modifying" it).
 
Personally, I think Sempatap is a bit of a waste of time.  Installing Sempatap is perhaps 50% as much work as installing "proper" insulation (e.g. 60mm of Kingspan) but offers 8% the performance (Thermal resistance of 10mm Sempatap = 0.213 m2K/W; 60mm of Kingspan = 2.61 m2K/W).  If you're doing all that work then you might was well go for a "proper" insulation like 60mm of Kingspan.
 
Some numbers (I've calculated the reductions in terms of percentage decrease in energy loss to aid comparison with the target of cutting carbon emissions from our housing stock by at least 80% by 2050):
  • U-value of uninsulated 9" solid wall = 2.1 watts per square meter per Kelvin
  • U-value of 9" solid wall plus 10mm sempatap = 1.47 W/m2K  (31% decrease in energy loss compared to uninsulated solid wall) (many thanks to Jessica for the updated figures)
  • U-value of 9" solid wall plus 10mm Aerogel (high performance but very expensive) = 0.8 W/m2K (62% decrease in energy loss)
  • U-value of 9" solid wall plus 32mm Aerogel = 0.34 W/m2K (satisfies building regs) (84% decrease)
  • U-value of 9" solid wall plus 60mm rigid foam = 0.34 W/m2K (satisfies building regs) (84% decrease)
Dry-lining using Kingspan is, admittedly, slightly trickier than applying Sempatap.  But it's something a competent DIYer should be able to do.
 
So yeah, Sempatap is better than nothing.  Covering the nation's houses in Sempatap might get us close to our 2020 emissions targets.  But then all the sempatap would have to be ripped out and replaced with decent insulation in order to hit our 2050 targets!.
 
I don't mean to put a downer on this.  Just trying to provide some comparisons.
 
Thanks,
Jack

 

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