Insulation slabs and tape around windows

Hello all.


Would anyone know how useful insulation tape would be around windows?


Currently, I'm renovating a house and someone advised me that for their new build they placed insulation tape around windows and upgraded their walls with insulated slabs, so to hermetically seal the walls and windows to prevent heat loss.



The builder thinks removing all the current windows and placing modern slabs on the walls and insulation tape around the windows is a costly amount of work and does not add that much value to the heat-loss prevention process.



Further, I was advised to do likewise for the ceiling, but the second story we propose to add to the house will have a heat-loss prevention floor. More overkill.


Forgive me if my terminology is off, as I'm not directly highly involved in the construction gig.



What do you think?

listermint

You must use 'airtight tape' not insulation tape. Around windows or any gap areas that would allow air through. It's an absolute vital step. Any builder not doing this as standard now should be viewed highly suspiciously in terms of keeping up with current standards.

Not doing it would be madness it's a cheap thing to do at this point in time. But the rewards for air flow exclusion are really high for the outlay.

listermint

listermint wrote: »

You must use 'airtight tape' not insulation tape. Around windows or any gap areas that would allow air through. It's an absolute vital step. Any builder not doing this as standard now should be viewed highly suspiciously in terms of keeping up with current standards.

Not doing it would be madness it's a cheap thing to do at this point in time. But the rewards for air flow exclusion are really high for the outlay.

Thanks for the reply. Thanks for correcting: yes, I meant "airtight tape". Do you think it worthwhile to remove existing windows, re-slab, fit airtight tape, and re-fit the same windows is a worthwhile investment? Plus the current walls have beaded insulation.



I know new builds would generally follow this modern standard, but would renovating an existing property, where we hope to keep most of the wall, bebetter in the logterm.


I'd love to know a general percentage of heat loss through windows. I know attic can be huge: upwards of 20%.

listermint

First. Are you replacing the windows ? How old are they why are you reusing them.

listermint

listermint wrote: »

First. Are you replacing the windows ? How old are they why are you reusing them.

The windows were fitted in 2015, so they would be new enough. We would be wanting to re-use these windows for sure.

listermint

TimberTones wrote: »

The windows were fitted in 2015, so they would be new enough. We would be wanting to re-use these windows for sure.

Ok . Then removing them would not be needed. What piece of work are you doing in terms of refurb that started this discussion? Just trying to understand the works that are or will be Happening.

listermint

listermint wrote: »

Ok . Then removing them would not be needed. What piece of work are you doing in terms of refurb that started this discussion? Just trying to understand the works that are or will be Happening.

We're converting the attic to a second story for a house. We're also improving the house by installing an air-to water system, new plumbing, and new electrics.



Someone advised us to re-slab the downstairs walls (house is 30+ years' old) and tape the windows while we're at it as now is the time and the improvements for heat retention are good (not sure how measurably good it is).

listermint

TimberTones wrote: »

We're converting the attic to a second story for a house. We're also improving the house by installing an air-to water system, new plumbing, and new electrics.



Someone advised us to re-slab the downstairs walls (house is 30+ years' old) and tape the windows while we're at it as now is the time and the improvements for heat retention are good (not sure how measurably good it is).

Really depends on the insulation that is there already. If not going to the expense of EWI then internally slabbing walls to a good depth 63mm plus would be a good idea and taping the windows prior to that is definitely a must. No windows don't have to be removed for this btw. Just the plaster reveal and then tape then slab the reveal with reveal board usually it's 22mm insulated for depth .

listermint

listermint wrote: »

Really depends on the insulation that is there already. If not going to the expense of EWI then internally slabbing walls to a good depth 63mm plus would be a good idea and taping the windows prior to that is definitely a must. No windows don't have to be removed for this btw. Just the plaster reveal and then tape then slab the reveal with reveal board usually it's 22mm insulated for depth .

No, we're not adding EWI as it's expensive and requires rework in a few years' time.



Thanks for letting me know that windows do not have to be removed, as this will safe both me and the builder time!


Sounds very doable and not as difficult as I initially thought.

listermint

TimberTones wrote: »

No, we're not adding EWI as it's expensive and requires rework in a few years' time.



Thanks for letting me know that windows do not have to be removed, as this will safe both me and the builder time!


Sounds very doable and not as difficult as I initially thought.

Note EWI doesn't require rework. Not sure where that information is from. Once it's done it's done.

muffler

Just to confirm that the windows do not have to be removed unless there is some other issue with them.

1874

TimberTones wrote: »

The windows were fitted in 2015, so they would be new enough. We would be wanting to re-use these windows for sure.

No expert, but, it doesnt sound like you should go to the bother and expense of removing windows, what you are suggesting is taping up the edges of the windows, it may help BUT
1. Your windows may not be airtight anyway, so it may actually be pointless. (its pretty much essential if the job is being done right and completely i.e. if you have an internal airtight membrane.

2. what are you taping to? if you dont have an airtight membrane across the interior of the house or there are other gaps, then the structure may not/most likely isn't airtight.

TimberTones wrote: »

We're converting the attic to a second story for a house. We're also improving the house by installing an air-to water system, new plumbing, and new electrics.

Someone advised us to re-slab the downstairs walls (house is 30+ years' old) and tape the windows while we're at it as now is the time and the improvements for heat retention are good (not sure how measurably good it is).

You're installing an air to water heat pump?? for hot water OR space heating?? unless the property is airtight and insulated, Im not convinced that is going to work at all for space heating, may just end up with large electricity bills.
Id be getting some calculations done on what insulation is needed and take it from there. airtightness is very important.

I've wondered and considered seeing if it's possible to create an external airtightness layer with some synthetic products, specific to the task.
But many homes with a hole in the wall for ventilation, it would nearly be pointless doing anything unless doing a complete upgrade of every aspect, Insulation and airtightness, anything else just makes people feel better because they have spent money on it.


Not sure what you mean by getting the downstairs walls re-slabbed? in plasterboard? or insulated plasterboard, who advised this?
If it is not drylined, this would be an ideal opportunity to install an airtight membrane/layer, more important than anything else you mentioned as most other stuff can be added later, anything else related to energy efficiency is like building a house without foundations.
imo internal insulation is potentially a problem, in that you may be creating a future problem for condensation and mould forming, internally somewhere.


What is the structure currently, imo the best type of structure to do upgrades to is one that needs an overhaul and has no dry lining.
Aside from no/less ripping stuff out, it should be easier to install an airtight membrane, possibly re-use or upgrade electrics and other services and then cover it all up, windows could be taped to and maybe upgraded later and EWI could be installed, that imo is close to the ideal upgrade/retrofit scenario.


Situations where there is good enough stuff to not throw out (like windows, but which may not be airtight) dilutes any effort to carry out upgrades to a high standard.


Whats the current structure? solid, cavity, dry lined?

muffler

muffler wrote: »

Just to confirm that the windows do not have to be removed unless there is some other issue with them.

No, the windows are new. They'll be staying put.

Plan is to add 2 inch insulated plasterboard to the internal walls and airtight tape around the windows.

Had an engineer out today and he recommended installing automatic vents to prevent condensation issues. He also recommended getting out a BER assessor to provide the best recommendations for airtight recommendations. What do you think about this?

muffler

TimberTones wrote: »

No, the windows are new. They'll be staying put.

Strange response. In your opening post you mentioned about the windows possibly being removed for the purpose of fitting air tight tape and when I confirm that they dont have to come out you emphatically state that they wont be moved. Im not sure why you asked the question to begin with.

1874

muffler wrote: »

Strange response. In your opening post you mentioned about the windows possibly being removed for the purpose of fitting air tight tape and when I confirm that they dont have to come out you emphatically state that they wont be moved. Im not sure why you asked the question to begin with.

I would interpret that staying put as meaning staying put in the house overall in the long run.

1874

TimberTones wrote: »

Plan is to add 2 inch insulated plasterboard to the internal walls and airtight tape around the windows.

Had an engineer out today and he recommended installing automatic vents to prevent condensation issues. He also recommended getting out a BER assessor to provide the best recommendations for airtight recommendations. What do you think about this?

No offence, but doesnt sound great at all,

2 inches of internal insulation? why 2 inches? its the insulation property, primarily the lambda value that is important, but internally? I just dont think its the right way to do it. There may be issues related to carrying out insulation externally that prevent it being implemented to the correct level, like being attached to another property.

I'd look up interstitial condensation/mould, airtightness around the windows and no-where else is just pointless imo, the whole house could be performing poorly in terms of airtightness, sealing the window frames with tape alone for the purpose wont do the job.
In my opinion, if not going to do or not able to do airtightness and insulation correctly, possibly better to not do it at all, thats not a joke, Im serious, because doing it incorrectly can lead to problems which a do nothing option wont experience and you'll have saved any money spent on it.



I dont know if BER assessors give recommendations for airtightness, thought they just measure the house as it is,
Id be wondering about your engineers opinions too,
In this day and age, it should be well known about potential problems related to insulating in certain ways (internally), you might just be spending money to achieve nothing.

muffler

muffler wrote: »

Strange response. In your opening post you mentioned about the windows possibly being removed for the purpose of fitting air tight tape and when I confirm that they dont have to come out you emphatically state that they wont be moved. Im not sure why you asked the question to begin with.

Hi, I was unsure at the start. People then reassured that I did not need to do it, so I moved onto the next question of how beneficial adding airtight tape would be.

am_zarathustra

Facing a similar issue with a renovation and after reading on here and doing a bit of research we are going to stick with gas heating for a couple more years until we can afford to externally insulate and replace the windows and move them out to prevent thermal bridging to create a decent level of airtightness before we move to a heat pump. Everything else did seem like messing and like it was just expensive bandaids. We will get a new door, seal the windows as are, check locking mechanisms, insulation under flooring, put proper attic insulation and seal the hatch, airtightness tape on the new patio doors etc etc for now. We will also prep the vents for direct mechanical ventilation.

The issues with internal insulation seem very hard to predict. There are some great threads on here with really generous explanations from people who clearly know their stuff. We might stretch to the mechanical ventilation now, after reading about it here and doing my own research it's a brilliant system.

1874

1874 wrote: »

No offence, but doesnt sound great at all,

2 inches of internal insulation? why 2 inches? its the insulation property, primarily the lambda value that is important, but internally? I just dont think its the right way to do it. There may be issues related to carrying out insulation externally that prevent it being implemented to the correct level, like being attached to another property.

I'd look up interstitial condensation/mould, airtightness around the windows and no-where else is just pointless imo, the whole house could be performing poorly in terms of airtightness, sealing the window frames with tape alone for the purpose wont do the job.
In my opinion, if not going to do or not able to do airtightness and insulation correctly, possibly better to not do it at all, thats not a joke, Im serious, because doing it incorrectly can lead to problems which a do nothing option wont experience and you'll have saved any money spent on it.


I dont know if BER assessors give recommendations for airtightness, thought they just measure the house as it is,
Id be wondering about your engineers opinions too,
In this day and age, it should be well known about potential problems related to insulating in certain ways (internally), you might just be spending money to achieve nothing.

I rang a BER assessor and the assessor said 52 mm cavity insulation would be good for the house. The automatic ventilation system would be a good approach to possible condensation problems with having an airtight house.



The engineer would only make structural recommendations, and would not provide a recommendation for anything insulation related.

am_zarathustra

am_zarathustra wrote: »

Facing a similar issue with a renovation and after reading on here and doing a bit of research we are going to stick with gas heating for a couple more years until we can afford to externally insulate and replace the windows and move them out to prevent thermal bridging to create a decent level of airtightness before we move to a heat pump. Everything else did seem like messing and like it was just expensive bandaids. We will get a new door, seal the windows as are, check locking mechanisms, insulation under flooring, put proper attic insulation and seal the hatch, airtightness tape on the new patio doors etc etc for now. We will also prep the vents for direct mechanical ventilation.

The issues with internal insulation seem very hard to predict. There are some great threads on here with really generous explanations from people who clearly know their stuff. We might stretch to the mechanical ventilation now, after reading about it here and doing my own research it's a brilliant system.

Tough choice, and one can have too warm a house. I know people who have had to turn off the underground heating in the thick of winter!

1874

TimberTones wrote: »

I rang a BER assessor and the assessor said 52 mm cavity insulation would be good for the house. The automatic ventilation system would be a good approach to possible condensation problems with having an airtight house.



The engineer would only make structural recommendations, and would not provide a recommendation for anything insulation related.

Look, you can listen to what you want, sounds a bit vague to me, but without doing a calculation of what the heat load is, what exists at the moment being told 52mm of cavity??? insulation is ok? over the phone? not all insulation are created equal in terms of their insulation properties, so what material insulation? Im not sure how they expect you to get the insulation into the cavity?? or they just assuming its there, Id be taking this advice with a large helping of salt, because it sounds like they dont even know they dont know what they are talking about which is concerning.
They gave this advice over the phone, how much can they actually tell for certain.

The vents might be an idea, I think Ventaxia do heat recovery vents and they might be the simplest proposition than a full mechanical ventilation system, not sure Id be convinced it would be more viable than a proper MVHR set up, cant really see how it would be airtight?
Personally, unless someone starts drilling samples of whats there, no one will know what insulatuon is in place or how good it is.
What are the makes of vents youre going for?

If I was in the situation of considering upgrades Id do it right and if necessary in stages rather than half measures, airtightness is a big deal and if its not done right or completely may nearly be as well to not bother. If you are in a situation where you are renovating and tearing stuff out, Id consider doing an airtight membrane and fitting ducting for a MVHR system if not a functioning ventilation system. Proper insulated and airtight windows could come later along maybe with EWI.
I guess it depends on how you view EWI, airtightness and what you are being told/hearing about it from people you are paying.

@1874

Thanks for the reply @1874.

Good points. Beaded insulation was added to the house a few years ago. Prior to this the walls had 2 x 1 lats with an inch of aeroboard. My wife's uncle knows the house literally inside out, so he could point us in the correct place to better insulate the house. Engineers and BER assessors might recommend things, but they do not, as far as I'm aware, take samples from the wall.

The automatic vents will be an addition to our home. They would help alleviate any possible condensation issue. Getting the correct airtightness of a home is complex and with different seasons at play, the vents should help any heat control issues.

We won't be doing EWI for now, but maybe down the line .

Good advice, 1874. Thank you!