Navitron Renewable Energy and Sustainability Forum

Green Building and Design => Energy Efficiency & Insulation => Topic started by: pantsmachine on May 13, 2018, 02:27:35 AM

Title: DIY internal cavity fill
Post by: pantsmachine on May 13, 2018, 02:27:35 AM
Hi all,
We have a 1980's semi detached bungalow which had been extended prior to our purchase. The extension went on to the gable end of the house and covered the gable end in its entirety. I had noticed a cold spot in the house over the years and one of the bedrooms did not retain heat and radiator was on high all the time.

These areas shared a commonality within the house, the old gable. Now strongly suspicious i popped a wall plate off and pulled the dryline box. Sure enough, reaching in & my hand was on the old harled external gable end wall and completely un-insulated.

Essentially, we had a 35 sqr mtr (I measured) un-insulated cold emitter in the centre of the house! I don't know about you but to me this is less than optimal?

After a little thought and reading on air flow, r values and disruption to be caused in rectification i settled on a solution.

I purchased a few bags of Micafil vermiculite from my local builders merchant and as the extension is two level i began on the ground floor.

I established where the vertical studs were in the wall, cut a rectangular hole high in the plasterboard between the first 600mm centre and began pouring in. I had a depth bob on string and after the first bag went in i took a sounding. Zero depth of was the result!

I had thought that the sound of pouring was not as anticipated, realistaion hit that i had a bags worth blowing about in my foundations! :)

Further investigation showed that the framework onto gable end was not 'water tight' and flowing product could migrate between the lower framework and the uneven gable end wall surface. The solution was a series of 1" holesaw holes spaced at 6" intervals just above skirting board and then injected with expanding foam to seal.

I then retested with another pour and achieved a moving depth sounding within the wall. I filled the first section and enjoyed the sound as it spread out laterally within the wall as far as it could. Once happy with the first partition I continued, repeating the pattern of a rectangular hole high in the plasterboard in between each 600mm stud section until i had filled the entire cavity with. The level above the high hole (6") was packed with a rockwool type insulation in each partition.

I could feel the change in air temp as i was pouring and moving on. Skin is sensitive and the best way i can describe the sensation is that the as previously described 'cold emitter' was being turned off as the job progressed It went from an insidious active negative to a neutral passive state if this makes sense? I completed the ground floor and the upper floor the next day with the same steps in plan.

The remainder of the job was a mild making good with the original plaster cut outs and plaster/paint. It went well and there is no sign that any modification has taken place.

If i remember correctly i used around 25 100ltr bags to complete the job. I had a nagging doubt with regard to moisture retention in the modified wall but to date (9 months) I have had no issues whatsoever. The product does not compact, lies lightly and i think any moisture can pass thru it cleanly and escape.

The R value is not massive in comparison to other products but in this particular case it was an ideal product to achieve a insulation level where there was none, no access and looking to make change with minimal disruption, there are no issues electrical cables/poly beads. I think a lot of people 'freeze' in place on how effective a product will be and do not act due a outcome that is not at 'The Max', which is a shame.

I honestly cannot overstate the improvement this made to our living environment and was kicking myself that the penny had not dropped with regard to the hidden internal gable end years before. The house heats up very quickly now and more importantly strategic radiator thermostats now ACTUALLY switch the radiators off! :)

Before we started i took some plasterboard temp readings and could feel how cold the board was with the back of my hand in comparison to my blood. Scale the back of the hand up over a 35sqr mtr area....

When the job was finished i remember walking about the spaces that the wall shares and being gobsmacked at the idea that i had shut this emitter off 24/7 for the rest of my life. I don't want to spraff off into profound statements but instead reflect on the amazement at this result as opposed to a hypothetical person who does not act due to the perceived lack of being the best R value. Off my soapbox now!

I hope this example is a solution for someone out there, cheers.

Title: Re: DIY internal cavity fill
Post by: billi on May 13, 2018, 07:45:04 AM
Good idea  pants

 i guess  there are several products to pour from the inside into a cavety   through the plasterbord   :)

the company Knauf

sells a similar idea for 12 euro a 100 l bag  in Germany , 

Title: Re: DIY internal cavity fill
Post by: pantsmachine on May 13, 2018, 08:19:34 AM
Thank you Billi,

It was defo an 'aha' moment when the solution presented itself. Quite funny when a bag dumped into the foundations! I used the same product to top up an awkward area in the remaining loft space where the boiler and its pipework is sited, as easy as pour it in, lightly spread and walk away.

 I am toying with the idea of making a hopper fed air blower with a 20 ft long 4" dia hose and camera to remotely top up my loft runs where inaccessible due to loft conversion (i think i ran in 100mm depth of fibre insulation 10 years ago pre-conversion) but my madness has deepened as has recommended reg's so why not? The headspace on the runs is there just need to access it somehow.
 Might be able to do something with an air compressor instead of a fan as the motive power leaving a couple of inches headspace for airflow. Same product being blown in, I will suggest to the Boss and see what she thinks! :)

Thank you for the link on the alt product, appreciated.

Title: Re: DIY internal cavity fill
Post by: stannn on May 13, 2018, 10:40:04 AM
Welcome pantsm/c
I thought that you would be interested in this old thread. Mike McMillan cured his problems with Silvapor, see page 3.,10868.0.html

Title: Re: DIY internal cavity fill
Post by: pantsmachine on May 13, 2018, 11:11:57 PM
Thanks for the welcome and the link to thread, I will be looking for a secondhand leaf blower asap! In this case the old gable end has been internal for 20+ years and was bone dry. In addition there is a 2 foot air gap between the bottom of the extension studwork and solem. There is no capillary moisture path from below which would be a nightmare, in retrospect i am a very fortunate unit. My main worry was moisture wicking through the plasterboard from inside the house and still having an escape path. The sheer scale of the wall combined with the lightness of the fill and relative dryness of the internal space and old gable practically guarantee no issues.

In saying that i never treat moisture control casually so even though i was sure i was sunny side up on this project I did some deep (for me) thinking and weighed up risk/reward.

As an aside and being aware of the potential for increased moisture as we tighten up airflow through the house i find it prudent to run a dehumidifier once a week in Winter  upstairs and downstairs on alt days to see what is there.  The skin knows when there is more in the air than should be but I guess i like to see what it will pull out in a few hours. :)

This wee Ebac is decent and we have used it for around 8 years with no issues.

This is an excellent site and has already effected change on me. On my return home i will be grasping the nettle on my restricted loft space access and will be installing a HUGE depth of top up insulation across the loft (while ensuring airflow remains). One that has nagged at me for years and this site acted as a catalyst, thanks to you all! :)

P.S Endoscopic camera ordered, the rest will fall into place over the next few weeks.

Title: Re: DIY internal cavity fill
Post by: pantsmachine on May 14, 2018, 05:26:01 AM
I have been running some figures and see that earthwool roll and blown cellulose would be the most efficient price/product combo in a loft zero damp risk environment. Is their a consensus on the upper limit of depth of product before it becomes a case of diminishing returns? Any anecdotal evidence?


Title: Re: DIY internal cavity fill
Post by: freddyuk on May 18, 2018, 06:49:10 AM
Interesting as I have a 1980's bungalow which we also extended so I have a cavity in the middle of the house. I can get to this in the attic and see right down to ground level so infilling with vermiculite would be easy to do. Mine is concrete block construction. I imagine there would be a draft through this void if it connects to the other cavities. The original insulation was 2inch Jablite so completely useless as much of it has been destroyed by rodents and various building works. I have not noticed a cold spot here but the extension has underfloor heating and 150mm of  underfloor insulation and the ambient temperature difference between old and new parts is around 10c. The old west end has 2 bedrooms which both have 2 external walls and these rooms are noticeably cold without the oversized rads I have installed. I cannot see a viable way to insulate the walls which again have Jablite batts dropped into the cavity so I was considering external cladding on this older section of wall or possibly cavity foam but not sure this would be effective with existing material in the voids.

Title: Re: DIY internal cavity fill
Post by: linesrg on May 18, 2018, 07:32:02 AM

I'm aiming for between 270 - 350mm of fibreglass once I've removed the old cold water header tank and finished completing the shower fan install.

Current recommendations are 270mm but the 350mm has been proposed.



Title: Re: DIY internal cavity fill
Post by: pantsmachine on May 18, 2018, 08:15:12 AM
Hello guys,

The silvaperl is expensive in comparison to blown cellulose but it is water resistant in comparison and effortless to install so i err'd on the side of caution for the cavity. In saying that, as the cold emitter can be felt turning off as job progresses its worth every penny.

Linesrg, thanks for the input. The leafblower is being picked up this weekend and i am going to go DEEP as the front 1/3rd of loft space with blown cellulose. This requires me cutting a hole in the wall to access it so this section in particular should look like a yeti after a hard Winter. Going to use a combination of earthwool roll and blown cellulose fill gaps to drift depths, ensure ventilation remains and then box off for all time (hopefully). :)

Title: Re: DIY internal cavity fill
Post by: Fionn on May 18, 2018, 09:12:19 AM
Was it perlite or vermiculite you put in?
I wouldn't have thought vermiculite would be suitable for this application as it absorbs moisture.

Title: Re: DIY internal cavity fill
Post by: pantsmachine on May 18, 2018, 10:37:51 PM
The link is in the 1st post. Its perfect for the application. Define risk of moisture in my application and why its unsuitable. The gulf tween thinking and knowing is vast. Try and make sure you know or you risk switching people off from a good idea. I try not to do that. Cheers.

P.S I was switching between terms in the 1st post, now rectified, thanks.

Title: Re: DIY internal cavity fill
Post by: Fionn on May 18, 2018, 11:14:41 PM
I have no doubt that you make a lot of friends with that attitude.

You used the two terms interchangeably in your opening post, which was the primary reason I asked. They are different materials, so your insulation is either one, or the other.

The second reason was that I have used silvapor perlite in a cavity wall myself, you may notice that several of the posts in the thread linked by Stannn are from myself.

As regard what I think, well it's based on what I know, which is that vermiculite absorbs more water and retains it more readily than perlite. As a result I'd imagine it would make it more likely to take water from one side of a cavity to the other.

Best of luck with your project.

Title: Re: DIY internal cavity fill
Post by: pantsmachine on May 18, 2018, 11:37:18 PM
Its not an 'attitude' in the classic sense and i am not looking for friends, at the same time i am not wishing to cause any offence.

I am looking to give and also exchange information preferably based on real world experience. Thanks for expanding the detail on your original question. It will give those reading this years down the road more food for thought and credence to your post.

In my project I gave careful thought to the environment that the product is being used within, whether that be the encapsulated gable down to solem, the position of that gable with regard to the solem on the new x & y axis of the extended house or the environment within the house, examples being- air volume within house, movement of air/ventilation and moisture sources within the home, ventilation within the cavity. I then switched to visualising minimal moisture from a dry environment wicking through the plasterboard and migrating through the loose filled product eventually to the loft space. I saw this balance to be acceptable and went forward.

I would advise anyone to do the same before commencing as every project is truly unique and I am just a random voice on the net, don't take my word for it!

As an aside, I have been using vermiculite offshore for decades to receive hazardous goods. We see all sorts of moisture laden environments within ships as we work worldwide and i can say with hand on heart that i have never seen sodden or even moist vermiculite, not even in the tropics after the vermiculite has been exposed for years to the environment, it does not readily take up moisture. I am not saying that you are incorrect with regard to its ability to absorb more moisture in comparison to another product but i see that as being similar to the less than optimal R value thought to stop a project going forward. It doesn't have to be perfect to work BUT each individual has to look at their project and see its risks. For many this will be a viable solution?

Ventilation in any form and at any level of the cavity would be of more importance to me that the difference in hygroscopic ability (I'm showing off now) of two similar products, Thoughts? I would also stick my neck out and say that the 1980's building stock in UK is decent with regard to being dry but most certainly not airtight and as such the majority of cavities will have built in ventilation which will be adequate to vent any moisture passing through the board from living spaces with a loose fill insulation such as this. I am putting this forward as a generalisation as i own 6 houses built within a few years of each other and have seen the similarity in construction up close during renovations.

I would be interested if anyone has figures or experience on the reduction of moisture transfer through plasterboard pre and post on a cavity? By this i mean does the insulated cavity resist moisture transfer from living space through the plasterboard into the cavity due to a more balanced temperature after insulation has been poured? I am possibly geeking out here beyond where i practically need to be..     Cheers and genuinely thanks for the input.

Title: Re: DIY internal cavity fill
Post by: JohnS on May 19, 2018, 04:22:58 PM
I have looked at the data sheet for Micafil available from the link in the first post.

It clearly states that one should not use Micafil in external cavity walls.

In about 2011, following on from the post that Stann linked to, I filled an unused chimney with Silvapor.  I provided a suitable drain at the bottom should moisture ever get in and run down the inside.

I have had no issues.

Title: Re: DIY internal cavity fill
Post by: pantsmachine on May 19, 2018, 11:02:15 PM
Good to know, I assume that is due to risk of rain being driven through for example a brick outer skin and into the cavity and then soaking the micafil?

I will report back if i have any issues with an external wall that is now an internal wall. Another type of beast and worth speaking about the varying scenarios.

I see Silvaperl V4 online for Euro 25 per 100 ltrs on a quick net search and Micafil cost us 19 per bag discounted at Travis Perkins but if i thought there was any risk of moisture i would definitely advocate the coated product for the little extra cost. Cheers.

Title: Re: DIY internal cavity fill
Post by: skyewright on May 20, 2018, 02:20:51 PM
I see Silvaperl V4 online for Euro 25 per 100 ltrs on a quick net search and Micafil cost us 19 per bag discounted at Travis Perkins but if i thought there was any risk of moisture i would definitely advocate the coated product for the little extra cost.
Can anyone advise a supplier of Silvapor (the coated perlite mentioned in the other thread), as opposed to Silvaperl (which seems to be coated vermiculite)? I've tried searching, but only seem to be able to find links & data that look out of date?

Title: Re: DIY internal cavity fill
Post by: JohnS on May 20, 2018, 04:42:01 PM
It seems that the original manufacturer, William-Sinclair went into liquidation and it is now being made by Dupre Minerals in Stafford.

I suggest calling them and asking.

Title: Re: DIY internal cavity fill
Post by: skyewright on May 21, 2018, 10:52:45 AM
It seems that the original manufacturer, William-Sinclair went into liquidation and it is now being made by Dupre Minerals in Stafford.
Thanks John. That's what I had missed.

Title: Re: DIY internal cavity fill
Post by: pantsmachine on July 11, 2018, 02:12:22 AM
To continue the diy insulation theme. We carried out a loft conversion 10 years ago and insulated the underfloor between downstairs ceiling and new conversion floor to spec. I had a look a few months ago and it turns out that there was a gap of approx 6" above the insulation and the underside of the loft conversion floor. It was not possible to access this space in a conventional fashion as the valleys were approx 18 foot long and only accessible from one end in the small remaining loft. (Sorry I have no photos).

Going on the 'what if' premise I brought together the following
10 mtr long wi if endoscopic camera (30)
3000w variable speed leaf blower (20 from Gumtree)
2 of tumble dryer vent hoses (from stock)
A homemade end nozzle  (from stock)
A rigid bamboo pole assembly  (from stock)
Duct tape (oh yes)  (from stock)
Dewalt drill  (from stock)
Plaster mixing paddle  (from stock)
A big mixing bucket (from stock)
150 kgs of cellulose insulation (165 for 10 bags)
Couple of dust masks  (from stock)

My wife absolutely ripped into me at the high likelihood of failure. Turns out i'm not quite as thick (in this case) as some think! Job went very well if insanely dusty in the beginning until i dialed in a process. Mixing up the insulation in a type of hopper really bulks it up before blowing it into place with the leafblower and dryer hoses. The camera works well and ensures that an airgap is left above the blown in cellulose to allow free travel of air. At the end of the job i ran in a few rolls of earthwool to top up on the existing insulation in the accessible part of loft and I am finally done with insulation....(for now). :)

The job was a hoot and extremely satisfying that it worked as hoped for, it will be interesting to see if there are tangible benefits over the next Winter. For reference, a 2000 watt leafblower would have had enough power to do the job easily. Oh yeah, I've now got a leafblower in my garden tool collection, bonus! exhappy:

Title: Re: DIY internal cavity fill
Post by: kristen on July 11, 2018, 06:29:43 AM
Bravo  :genuflect

Title: Re: DIY internal cavity fill
Post by: biff on July 11, 2018, 07:39:38 AM
Indeed ,,Well done Pantsmachine,
                There will be a few of our members who will avail of your method, including myself.
      Thank you.

Title: Re: DIY internal cavity fill
Post by: offthegridandy on July 11, 2018, 10:44:36 AM
Aye, well done and how nice to hear that bodgenering is still alive and well.


Title: Re: DIY internal cavity fill
Post by: pantsmachine on July 11, 2018, 10:20:20 PM
Thanks Lads, glad you like it!

The cellulose fiber is made in Ireland

It bulks up about 40% in the hopper when hit with the paddle. Also worth using a beachtowel or similar across the valley entryway to stop blowback during filling, really gets into cracks and gaps so chances at full insulation coverage are much improved.  I look forward to reading of anyone else adventures in insulation & 'what if', great fun!  ;D

Title: Re: DIY internal cavity fill
Post by: Mike McMillan on July 13, 2018, 06:17:49 AM
 used this system a few years ago, blowing it into a a 12" space above the kitchen and bedroom in a 1850 house...the dust was horrific and silver pour started trickling out of any tiny cracks around window and door frames etc. Persevered, but I NEVER want that taste in my mouth or eyes again!



Osborne Bay

Title: Re: DIY internal cavity fill
Post by: pantsmachine on July 14, 2018, 05:10:56 AM
:) Its not the most comfortable job I have ever done and can't say i fancy Silvapour as a condiment. Definitely a mask for anything like this and if i could i would have worn a positive pressure variant. Sadly i don't have that at home so went with the taste of paper and interesting nose production! Kept telling myself, 'its a one time job'!

Title: Re: DIY internal cavity fill
Post by: gravelld on August 26, 2018, 08:43:57 PM
I'm not 100% following this case, but I reckon cavity walls enveloped by extensions, opening into cold lofts are a big-ish problem nationwide. Ours had three, confirmed as problems with an IR camera. I filled them with EPS bead and a PVA/water mix.

Title: Re: DIY internal cavity fill
Post by: pantsmachine on September 02, 2018, 04:34:01 AM
I agree they are a well hidden leach of energy. How did you isolate the electrical cables in the walls from contact with the polystyrene beads? Interested as i avoided poly beads due to the reaction between the two plastic types? If you didn't know, don't freak but worth your while to read up on. Examples below.

Title: Re: DIY internal cavity fill
Post by: gravelld on September 05, 2018, 07:36:13 PM
Sheathed in nylon (the ones I could see  :crossed )

Title: Re: DIY internal cavity fill
Post by: pantsmachine on September 06, 2018, 12:12:57 AM