Insulating timber door with Aerogel?

[low_and_there]

We’ve got a lovely original glazed timber door we’d like to improve the thermal efficiency of. I’ve got an idea on insulating it but keen to hear any thoughts/concerns or suggestions:

 

1) Add a double glazed layer behind the glazing on the inside of the door - sealing as much as poss to reduce risk of interstitial condensation

 

2) Adding 10mm of Aerogel to the rest of the door, framed around with a timber edging, applying a top layer of 3mm ply (adding beading to mimic the original appearance on the interior)

overall increasing the thickness of the door from 44mm to 57mm (will need to adjust door frame too!).

 

I haven’t found any examples of using Aerogel on a timber door so wondering if there may be issues I’m oblivious to.

 

thanks in advance

 

 

Edited April 8, 2022 by low_and_there

[Simplysimon]

any chance of a pic to let us get a better idea?

[Iceverge]

What exactly product are you considering using? 

 

A quick Google shows it's very dear, about £100/m2 

 

 

[JohnMo]

Why not use 15mm PIR.  Aerogel is super expensive.  Same insulation value about 1/3 the cost

[JohnMo]

Or is that 1/10 the cost

[Radian]

Or a few layers of corrugated cardboard possibly for free 😄

I think the idea is to keep it horizontal to limit convection. Also it needs to be vapor sealed to prevent it getting damp from condensation on the cold side.

Edited April 8, 2022 by Radian

[low_and_there]

Hi @JohnMothank for the suggestion but the entry hallway is so narrow that I can’t go beyond adding 13mm in total, hence thinking of using Aerogel given that it is the thinnest insulation I believe exists in terms of U-value/mm. Aerogel comes in many forms, ideally I guess it would make most sense to us use it in “board” form but I’ve not found it available in the UK yet.. seems the most common one available is in “blanket” form. 

 

i am aware it’s expensive but it’s within my budget for the overall door work that is needed - approx £155 will get me sufficient to do the door. Appreciate some people may think that amount of money on 2sqm of insulation is absurd but hey, each to their own.

 

@Radian thanks for highlighting the need to vapour seal! Such a good point that I’d overlooked!
 

a question - Aerogel is used extensively on vertical surfaces.. maybe I’m misunderstanding your comment - what should be kept horizontal? Thanks!

 

hi @Simplysimon I’ve not got a photo to hand, will try sort - but picture a narrow hallway typical of a 1900 brick built mid-terrace, with a 80cm wide door and very little wiggle room either side

 

[tonyshouse]

I made my own door and had 30mm pir outside and 10mm inside 100mm overall thickness 

[Radian]

46 minutes ago, low_and_there said:

a question - Aerogel is used extensively on vertical surfaces.. maybe I’m misunderstanding your comment - what should be kept horizontal? Thanks!

 

I was talking about corrugated cardboard. Seriously, it has a reported R-Value similar to other common insulation materials:

 

Typical R-values

Material	RSI-value (m2·K/W)	R-value (ft2·°F·h/BTU)
Icynene spray	0.63	3.6
Open-cell polyurethane spray foam	0.63	3.6
Cardboard	0.52–0.7	3–4
Rock and slag wool batts	0.52–0.68	3–3.85

 

To avoid convection on a vertical surface, you would align the flutes horizontally.

Insulation is primarily a matter of trapping air (one of the lowest thermal conductors) in an envelope with low thermal conduction/contact surface area. Fluted cardboard sheet meets these requirements. The downside is that it is not as robust as mineral wool of the other cellulose products. But sandwiched between ply sheeting it should perform equally well - provided it has a vapor control layer to prevent condensation forming on the cold side.

[Iceverge]

Could you insulate externally ?

 

Presumably you'd have more space .

[Conor]

Aerogel is a soft, fibrous material, a bit like cellulose, and hence is quite soft and powdery, hence only available in roll or blanket form. Its not the nicest to work with, reccomend toy get a foil backed sheet to to your required dimensions.

[low_and_there]

Hi @Conor thanks for the tip - I’ve found it in Switzerland available in all sorts of forms, including in board form - although with a cement face.. Do you know any supplier that makes foil backed sheets to spec? That’s a great idea! 

 

@Icevergewe want to retain the external appearance of the door so not really an option to do external. But thanks for suggestion.

 

[JohnMo]

Give these an email or call.

 

They supplied mine cut to specific size, quick turnaround.

 

http://www.enviroform-insulation.com/

[Temp]

20 hours ago, low_and_there said:

Aerogel comes in many forms, ideally I guess it would make most sense to us use it in “board” form but I’ve not found it available in the UK yet

 

Pure Aerogel is the best insulation but in its pure form it's quite fragile as it's something like 99% air. Typically they mix it with something to make a blanket like insulation but that reduces its insulating properties.

 

[Conor]

@low_and_there enviroform will cut their sheets to suit. Give them a call. Very helpful and fast.