Voids

Foam applicator gun
Foam applicator gun
~ unit cost £30 + installation £30 = £60



Page summary…

Successfully draught proofing a home by preventing uncontrolled air ingress/egress is essential to improving comfort, reducing energy costs and managing moisture… damp.

We’ll look at some common appropriate and inappropriate voids, questioning their objectives and whether they are achieved. We’ll ask if they are functioning correctly and being operated appropriately before considering what practical affordable improvements are possible.



On this page

Audit

Projects

 

Related on another page…

  • Doors
  • Windows
  • Paper and paint

 



Background…


Aims – Draught-proofing is perceived as easy and affordable, something a homeowner might tackle themselves following a visit to a hardware store to purchase a few low-cost products. [Ref – DECC] Improving the performance of doors and windows is of obvious concern, however, our existing homes have become perforated with a history of inappropriate and often hidden holes that go undetected. The current approach to draught-proofing fails to deliver successful results.


Objectives – Air moving through a building takes the path of least resistance. When air ingress/egress is restricted at one point in the fabric the air pressure will increase the rate of air passing through at other locations.

Hypothesis – When blindly installing draught-proofing product the results are more often disappointing. Is it possible to achieve better results with a more thought-through methodology? Start with larger to expose the small. Success comes from being universal.



Methodology…


Audit

Does it work and is it used appropriately?

  • Don’t beware the temporary measure
  • Start with the large
  • Expose the small
  • Be universal
  • Managing moisture

Checklist

  • Chimney voids – both top and bottom
  • Kitchen and bathroom – dysfunctional vents and service voids
  • Floors and ceilings – gaps and cracks
  • Miscalanus  holes – obsolete unimpeded vents and unnecessary air-bricks

Common voids…

Chimney voids

Fireplaces

Chimney pots


 

Sub-floor voids

Air-bricks

Gaps in floorboards


 

Roof and ceiling voids

Attic spaces

5mm continuous gap

Hairline cracks


 

Service voids

Kitchen and bathroom



Projects

The following projects are intended as a means of developing transferable skills, understanding the objectives and applying the principles required to achieve successful results. They are not intended as a comprehensive how-to instruction manual.



Expanding foam applicator gun

Foam applicator gun

Expanding foam filler is an invaluable material for sealing up draughts and a versatile adhesive for securing things in place without the need for mechanical fixings such as screws and nails.

Read more...

 

Why – Don’t beware the temporary measure

Foam filler is ideal for preventing uncontrolled air ingress/egress “draught-proofing”. It is a good insulator, preventing the conduction of heat and also preventing moisture vapour from migrating to cold surfaces causing interstitial condensation.

Historically, Polyurethane foams (PUFs) are manufactured from petrochemical-based products and use potentially toxic blowing agents. Understandably, there has previously been some resistance to the use of PUF’s, however, much improvement has been made. Polyurethane Foams: Past, Present, and Future

A more pragmatic approach recognises that when used in moderation a small amount of Expanding Foam can be very beneficial and therefore an immediate game-changer for reducing energy consumption, lower heating bill and improved comfort.

Essential around the frames of windows and door, or when assuring insulation board is airtight. Expanding foam filler is also invaluable as an easy win or temporary works or temporary measure.

 

HowAlways read the instructions

Unlike disposable canisters, a foam applicator gun provides full control. The application can be in moderation and the canister can be closed off and reused on another occasion to avoid waste.

Expanding polyurethane foam is essential for installing doors and windows. When a frame is airtight, constructed to a good standard or improved with secondary glazing air will more easily be sucked around the frame which will cause degradation and ultimately failure.

Quick and easy to use, the results are immediate. Expanding foam can also be used for temporary work, then cut away and clean off when ready to proceed with a more permanent solution.

 

What – Materials and equipment

Unlike disposable canisters, a foam applicator gun provides full control. The Expanding Foam can be applied in moderation, then the canister can be closed off and used again on another occasion, avoiding waste.

If not closed off correctly or left empty any remnant foam left behind inside the applicator gun will set hard and render the gun unusable; always have a spare canister ready to replace an expired can.

It is also recommended to have a canister of gun cleaner to hand. It won’t dissolve cured foam inside a gun (or elsewhere) but it will dissolve sticky fresh foam from an accidental spill.

Before procuring and using a foam applicator gun it is of advantage to understand the avoidable pitfuls.

Here are 10 top tips…
https://www.neighbourhoodconstruction.org/foam-applicator-gun/

 

Foam applicator gun – Screwfix £19.99
http://www.screwfix.com/p/no-nonsense-foam-applicator-gun/28483

Expanding foam gun grade – £5.99
http://www.screwfix.com/p/no-nonsense-expanding-foam-gun-grade-750ml/87934

Foam gun cleaner – £4.99
http://www.screwfix.com/p/no-nonsense-foam-gun-cleaner-500ml/60133

 



test image

Thermafleece

Extensive volumes of air ingress/egress can be slow and imperceptible. By starting with the larger holes a reduction in air change may also be imperceptible as air will consequently move through smaller holes more quickly. By starting with the large we expose the small and progress can be measured when the wind begins whistling through the keyhole.

Read more...

 

WhyStart with the large… and expose the small

Chimneys voids, top and bottom
Closing off the chimney inside at its base in the fireplace is relatively easy, by ‘tightly’ plugging the hole, this could be quickly achieved with a foam applicator gun. However, this can lead to unintended consequences. If air can enter the chimney at the top, cold air will become trapped as a frost pocket and trapped in place will result in cold spots on the internal room surface which will attract warm moist air which will begin to manifest the symptoms of damp. A disused chimney should also be capped to prevent the accumulation of water ingress which is no longer evaporated my the use of the fire through draught.

A disused chimney would therefore best be closed off both top and bottom.

 

HowMake a plan

Close off with tightly packed insulating fleece, both bottom and top then cap off the pot with a purpose-made or bespoke cowl – an example is given.

Survey
The East chimney has 12 pots yet below there are only 8 fireplaces. Identifying which pots connected to which fireplace is a challenge. It would be preferable to close all of the pots, even those chimney voids not leading to a fireplace. These voids may also cause ‘frost pockets’ detrimental to the property. It is also possible that these voids may connect to next door and could be in-use. Closing off an in-use chimney would be negative, liaising with the neighbouring property will be required. Careful investigation is required.
For reference, these pots shall be numbered from left to right (north to south) as pot 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 and 12.
The West chimney has four pots, two of which are for the joining property. Identifying the pots connected to No.64 should be straight forward.
For reference, these pots shall be numbered from left to right (south to north) as pot 13 and number 14.

Convention, assumptions and hypothesis
Often, but not always, pots to the outside, connect to the top floor and those to the inside go to the bottom.
Pot number 5 has a gas cowl, it is reasonable to assume this pot once connected to the old gas-powered stove in the kitchen on the lower ground floor at the very bottom of the chimney.
The Stack has been modified, the top has been rebuilt possibly due to a problem with the flaunching. This could be the result of a change of fuel – from wood to coal. The replacement bricks are late Victorian or possibly Edwardian or later and are more ‘closed’ to moisture vapour.
The two pots to the outside of the stack (1 and 12) and the two at the centre of the stack (6 and 7) are modern pots (late 20th century). It may be that these voids have always been unused and not connected to any of the fireplaces. These voids may be part of the overall structure of the whole stake.
Pots 8, 9, and 11. Have been replaced with Victorian pots, possible due to a change of fuel. The Victorian pots are designed to reduce the draw when switching to burning coal rather than wood. Pot 8 has a missing cowl and therefore should easily except a new metal cowl. Pots 9 and 10 will require a bespoke lead capping. The other pots are original

Methodology
Using sisal twine lower sash weight and copper bells down each chimney to identify its fireplace. Note length lowered and listen internally for weight and bells arriving in the fireplace. Coordinate with neighbouring property.
Roll tightly together 2 batts of hemp fleece and tie with sisal twine.
Cap with a cowl.

 

What – Materials and equipment

Chimney capping cowl – for liability use a product designed for the purpose. Lead-sheet can also be used when a cowl won’t fit, suitable short offcuts may be found at a local scrap metal merchant rather than purchasing a whole new roll.

Capping cowl or Lead

– discount for multiple cowl units

– reclamation

 

Material choice – Sheep wool, Hemp wool or Mineral wool loft insulation,

Hemp insulation – Celtic Sustainables £186 per 48 batt pack – Roll = 50 x 370 mm x 1200 mm x 48 batts. £? /m2

Sheeps-wool – Celtic Sustainables £26 per 13m roll. – Roll = 50 x 370 mm x 13,000 mm. £? /m2

Quantifying – numbers and volumes.

 

Chimney capping cowl – Travis Perkins £25.66
https://www.travisperkins.co.uk/Mad-Capping-Cowl-Powder-Coated-Terracotta/p/954174

Hemp insulation – Celtic Sustainables £186.00
https://www.celticsustainables.co.uk/thermafleece-natrahemp-thermal-acoustic-insulation/

Sheeps-wool insulation – Celtic Sustainables £26.00
https://www.celticsustainables.co.uk/thermafleece-cosywool-sheeps-wool-insulation/

 

Project plan - an example is given

1. Brief

Extensive volumes of air ingress/ egress can be slow and imperceptible. By starting with the larger holes a reduction in air change may also be imperceptible as air will consequently move through smaller holes more quickly. By starting with the large we expose the small, progress will be measured when the wind is whistling through the keyhole.

Closing off the chimney inside at its base in the fireplace is relatively easy, by ‘tightly’ plugging the hole, however, this can lead to unintended consequences. If air can enter the chimney at the top, cold air will become trapped as a frost pocket and trapped in place will result in cold spots on the internal room surface which will attract warm moist air which will begin to manifest the symptoms of damp. A disused chimney should also be capped to prevent the accumulation of water ingress which is no longer evaporated my the use of the fire through draught.

A disused chimney void must therefore be closed off both bottom and top.

2. Design

Close off with tightly packed Hemp fleece, both bottom and top. Cap off the pot with a purpose-made or bespoke cowl.

The East chimney has 12 pots yet below there are only 8 fireplaces. Identifying which pots connected to which fireplace is a challenge. It would be preferable to close all of the pots, even those chimney voids not leading to a fireplace. These voids may also cause ‘frost pockets’ detrimental to the property. It is also possible that these voids may connect to next door and could be in-use. Closing off an in-use chimney would be negative, liaising with the neighbouring property will be required. Careful investigation is required.

For reference, these pots shall be numbered from left to right (north to south) as pot 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 and 12.

The West chimney has four pots, two of which are for the joining property. Identifying the pots connected to No.64 should be straight forward.

For reference, these pots shall be numbered from left to right (south to north) as pot 13 and number 14.

Convention, assumptions and hypothesis

Often, but not always, pots to the outside, connect to the top floor and those to the inside go to the bottom.

Pot number 5 has a gas cowl, it is reasonable to assume this pot once connected to the old gas-powered stove in the kitchen on the lower ground floor at the very bottom of the chimney.

The Stack has been modified, the top has been rebuilt possibly due to a problem with the flaunching. This could be the result of a change of fuel – from wood to coal. The replacement bricks are late Victorian or possibly Edwardian or later and are more ‘closed’ to moisture vapour.

The two pots to the outside of the stack (1 and 12) and the two at the centre of the stack (6 and 7) are modern pots (late 20th century). It may be that these voids have always been unused and not connected to any of the fireplaces. These voids may be part of the overall structure of the whole stake.

Pots 8, 9, and 11. Have been replaced with Victorian pots, possible due to a change of fuel. The Victorian pots are designed to reduce the draw when switching to burning coal rather than wood. Pot 8 has a missing cowl and therefore should easily except a new metal cowl. Pots 9 and 10 will require a bespoke lead capping. The other pots are original

3. Programme

Methodology

Using sisal twine lower sash weight and copper bells down each chimney to identify its fireplace. Note length lowered and listen internally for weight and bells arriving in the fireplace. Coordinate with neighbouring property.
Roll tightly together 2 batts of hemp fleece and tie with sisal twine.
Cap with a cowl.

Equipment

  • Scaffold – 2 cushioned boards, plank and ladder.
  • PPE – harness, SRT rope, shunt etc
  • Strong sisal twine, (with length markings).
  • Weight – small sash weight.
  • Bells – 22mm copper plumbing pipes, attached to a weight.

Materials

  • 11 Cowls – negotiate bulk purchase price as a Travis Perkins account holder a single unit can be purchased for £15 inc
    Travis Perkins – £25.66
  • 2 Lead Cowls – RJ Coles, metal recycling 2@ 12″ x 12″
  • 1 Gas Cowl – the previous solution has been to fill with expanding foam
  • Sheep wool – Celtic Sustainables £26 per 13m length – Roll = 50 x 370 mm x 13,000 mm. £5.40 /m2 (33.6 metres 3 roles required – £78)
  • Hemp wool – Celtic Sustainables £186 per 48 batt pack – Roll = 50 x 370 mm x 1200 mm x 48 batts. £5.40 /m2 (28 batts required – £108.50)
  • Let’s go with hemp batts
  • Strong sisal twine (for tying into rolls)

4. Schedule… when will it happen

  • Procurement of materials and equipment
  • Installation
  • Evaluation and peer review.

5. Team… who will be involved

  • Procurement of materials and equipment
  • Installation
  • Evaluation and peer review.

 



Caulk applicator gun

Caulking

Decorators caulk is an affordable and easy way to prevent air-ingress up from between the floorboards. Using the trigger gun the gaps are filled, being water-soluble, excess decorators caulk can be wiped away with a sponge and any residue remaining on the boards can be lifted with WD40, an oily rag, once the caulk has cured.

Read more...

 

WhyStart with the large“]

The small gaps between floorboard can add add up to a large hole, once again allowing slow, imperceptible air-ingress.

 

Howmake a plan

Design and Programme

 

What – materials and equipment

Evaluation

 

Screwfix Sealant adhesive dispenser gun – £19.99
https://www.screwfix.com/p/p-c-cox-sealant-adhesive-dispensing-gun/4379h

Screwfix – White caulk – £1.39
https://www.screwfix.com/p/no-nonsense-decorators-caulk-white-380ml/43686

Decorators Centre – Brown caulk – £1.87
A box of twelve tubes is sufficient for a couple of rooms for a little over a pound per tube.
https://www.duluxdecoratorcentre.co.uk/ddc-decorators-caulk

 


Results…



Discussion…


Practitioner stories

76-year-old non-scientific woman gathered the following

76-year-old non-scientific woman gathered the following – Whis Collis
https://www.neighbourhoodconstruction.org/2018/01/15/76-year-old-non-scientific-woman-gathered-the-following/


Capping two chimneys

Capping two chimneys – Thomas Richards
https://www.neighbourhoodconstruction.org/2021/02/16/capping-two-chimneys/


Don’t beware the temporary measure

Don’t beware the temporary measure – Sarah Jones-Morris
https://www.neighbourhoodconstruction.org/2018/01/15/dont-beware-the-temporary-measure/


A beautiful 1850’s Semi – a history of chimney damp spots

A beautiful 1850’s Semi – a history of chimney damp spots – Simon James Lewis
https://www.neighbourhoodconstruction.org/2018/03/03/a-beautiful-1850ssemi-a-history-of-chimney-damp-spots/


Foam applicator gun

Foam applicator gun – top ten tips and tricks
https://www.neighbourhoodconstruction.org/foam-applicator-gun/


Blog category – voids
https://www.neighbourhoodconstruction.org/category/voids/


Conclusion…


Workshops

Advice and support