I did consider rockwool for underneath but actually getting a vapour control layer or breathable membrane in place to reduce air infiltration seemed tricky as I was working in cramped conditions with maybe a 45cm space under the floor with a roll of heavy material. Older homes are most likely to have suspended timber floors. If your floor is above an unheated cellar or basement you will need to fit the insulation snugly between the joists and secure in place with netting if required. One of the main reasons for this is we are unsure how the insulation will cope with the under floor moisture and it causing condensation in the rooms above. Why would you need one if fitting from the top and not from below or is it just because you cant ?
Depending on where you live, and who you buy your energy from, we can help you with grants and support. This breathable characteristic makes it attractive for use in older and heritage homes as it doesnt block the movement of moisture. How about using Spray Foam Underfloor Insulation? If you live in the green or blue areas, we can sign you up to your local priority services registerifyou're over 60 or you rely on electricity for medical or mobility reasonsoryou have a hearing or visual impairment or a long-term health condition. Cookies are small text files that can be used by websites to make a user's experience more efficient. One is that will reduce the average u-value of the floor. b) When insulating from below without removing the floorboards then a vapour permeable membrane is used below the insulation to both retain the insulation and to make sure that it does not lock any moisture into the joist area. This would drop the vent below the level of the joist and allow me to insulate above it. Battens fixed under the board hold it in place or a plastic friction fit support can be used. Ive been reading the best practice guidance from BEIS on floor insulation and it suggests that 4in joists are susceptible to cold-bridging. It can also be added on top of a solid floor, such as concrete. Because the PIR board is on supports I would place mineral/natural wool or other on the roll insulation in space between the joists resting on PIR board. It will also help reduce your propertys carbon emissions and lower utility bills. Just after some advise if this is a viable solution But it wont reduce heat loss through flooring significantly.
My house dates from 1912 and is a Scottish sandstone/brick semi-villa with about 150m2 of ground floor space. Many older houses with suspended timber floors have big draughts and inadequate floor insulation; this can cause cold feet as well as higher energy bills. The gap inside is two bricks in height. Hi Jon
You can see the tell tale staining of the carpet round the skirting boards as air from under the suspended floor continuously flowsthrough the carpet. It is only a couple of days since it was installed. It will also stop air, wind and high air pressure coming with storms and pushing this cold air all the way up to your house. The troughs of netting are then filled with blanket-type insulation. I do think the cons section for the PIR insulation should be updated to note that it is highly combustible and in combination with timber floors could present a significant fire risk. Radiator barely comes on now, whereas it struggled to maintain required temperature before despite being oversized for a modern weather compensated boiler system. However, youll need a low thermal resistance if you have underfloor heating in place, as the underlay will end up blocking the heat from rising up through the floor. I have yet to see a good way of overcoming this when insulating from above. The floor to be insulated rests on 4 brick wall supports with gaps here and there to allow for air circulation. notice.style.display = "block";
Types of home insulation explained, Loft insulation, the complete guide to types & costs, Customer Warranty for Installation Services. For instance, insulation that comes in a wool-like structure traps tiny pockets of air within the fabric, and its this trapped air that acts as the heat barrier. The initial price may seem steep seeing as the saving is only approximately 50 per year. Insulating a suspended timber floor can eliminate floor draughts and reduce heat loss through the fabric of the floor at the same time. Insulating solid floors is where youll need to err on the side of caution, since raising the height of the floor can cause more work (trimming door heights, refitting radiators, rewiring plug sockets etc) and consequently a greater expense. We have just moved into a 80s bungalow with suspended flooring that has a 46 space under the floorboards. There is no insulation and lots of gaps in the tongue and groove so letting in huge amounts of air conditioning at ground level. var notice = document.getElementById("cptch_time_limit_notice_55");
I would be quite surprised if it was one continuous timber between the two properties; there would be extra unnecessary cost and handling issues with having longer timber for no benefit. Thanks for the considered feedback. Historic England (2012). I have read that traditional insulation such as fibreglass, PIR board or rock wool does not produce an air seal, and It can also move and sag, causing drafts to appear and loosing its thermal resistance over time becoming ineffective. Properties built pre-1920 often didnt have air bricks for ventilation or a DPC (Damp Proof Course) so damp may be a problem that needs sorting before you think about floor insulation. Time limit is exhausted. The problem we have is the underside of the boards supporting the insulation is damp. Probably a silly question but how about insulating the suspended timber floors on the first floor of a house as opposed to the ground floor? I can appreciate your confusion. Moist air from these rooms should be extracted to the outside rather then being allowed to condense on walls, which could lead to damp or mould. I like the idea of draught excluder; that seems a good solution if you run a batten the full length of the insulation edge along the joist. remove the existing floorboards, insulate and relay the floorboards. Quality mineral wool will stop draughts as you can push it near walls and will work really well in the cold days and it is much cheaper. I was thinking of some type of sheeps wool insulation but would it need a damp proof layer and some form of suspension even though it is not for a ground floor room. Although your installer will normally arrange this for you, it is your responsibility to comply. If a house is being refurbished or is empty and the floors are in poor condition then ripping out the existing floors and insulating from above would be easier. Would you still need to have the VCL and layer to support the insulation? Marketing cookies are used to track visitors across websites. Some of this i understand is down to maintenance and an old property..the water table under the property alters as in when it rains heavily there is water visible and it may hold water several inches and then drain off. See the left hand image below as an example. Unless youre planning to replace all the floorboards, try to lift only a few at once to keep damage to a minimum. function() {
If you have an older property that is designed to be breathable or you have concerns over damp then Id go for a natural / breathable insulation materials such as sheeps wool insulation which can cope with more moist conditions and the requirements of traditional properties. Kind regards I would like to screw few metal brackets to the walls supporting joists and place PIR board on them. a) If you are insulating from above as you describe then you use a membrane to block moisture (what they call a vapour control layer which is impermeable to water) and put it above the insulation and below the new floorboards. Insulation can be laid over the existing floor, but if a floor is being replaced, this is a perfect opportunity to improve the standard of insulation. Keeping the thickness of your insulation to a minimum will reduce the likelihood of having to make costly alterations to door openings, stairs and other fixtures as a result of the increase in floor height. Air can seep through the carpet, even if it has an underlay, bringing with it dirt and dust which can discolour the carpet if it is a light colour and depositing dust on the skirting board. I would be slightly nervous of the foil preventing any moist joists from drying out from below but it depends on the dampness and airflow in your cellar. Measuring and cutting them is very easy with a small handsaw outside but it becomes a little more difficult when you are on your back under the suspended floor with a face mask on. Current thinking is that the breathable membrane can be used to provide the support for flexible insulation if the floors are insulated from above with a vapour control layer covering the insulation. Hi Miles In older houses it can be a challenge to insulate to get warmer rooms without creating other problems. Any major changes to your home must meet with your local building regulations, so if youre doing the install yourselves, its your responsibility to comply. Even when working from below insulating over the joists is problematic, unless you have very easy access to the underside of the suspended floor from a cellar which is rare in most houses. Contractor came back saying that cant install insulation under kitchen if cabinets in place, or bathroom because it is tiled. See SeeInsulating A Suspended Timber Floor From Above Floor. Insulating a concrete floor might take 14 years to pay for itself, but this will reduce as energy prices continue to rise. Domestic heat pump systems for your house, Air source heating vs. ground source heat pumps. I was planning on just getting the insulation, staple gun and netting then placing it under all gaps and fixing in place. Where lino or luxury vinyl like Amtico is installed then lifting the floor is not normally an option. If you can feel a strong draught as you go up the stairs then there is probably some opportunity to reduce heat loss upstairs.Note: When reducing draughts do consider the impact of less airflow on areas which produce a lot of moisture, such as kitchens and bathrooms. I am doing the same job soon. Hope this helps and all the best with your project. What are the pros and cons of using foam backed radiator reflector pinned to the battens to reduce the bridging effect of the joists? I thought actually any membrane (albeit breathable) would be the same as a netting if not worse as would create less air flow inside. See Using Robotics for Underfloor Insulation of Suspended Timber Floors.The Department for Business, Energy & Industrial Strategy (BEIS) has also produced a Guide to Best Practice on Retrofit Floor Insulation for Suspended Timber Floors. Carpets can also make a difference but they are not air tight and they will not fix draughts through the skirting boards. With rigid board you can measure the gap between the joists and cut the board accordingly. The U-value is a measure of how quickly heat will travel through the floor. See our guide to draught-proofing, or read on for more about floor insulation. Not always perfect but you can fill any gaps with expanding foam and also tape to prevent any air movement. I have seen examples where netting is used from underneath but this is not considered so effective at eliminating draughts. Air bricks should be cleared of debris to allow good airflow. Required fields are marked *. Check that the joists supporting the floorboards are in good condition and dont show any signs of wet or dry rot. By installing the additional vents (I am presuming additional air bricks) the sub floor space should be better ventilated in the future. It would be good to see some comment on Building Regs for thermal upgrades. Unless you can identify another source, I would presume that the damp soil smell entered the house when floorboards were lifted to install the insulation. House is very cold and requires a breathable solution for the floor. In the case of adding extra insulation to your existing floor these may include making sure that the rooms on your ground floor still meet the minimum room heights, that you achieve minimum U-values (the standard measure of thermal performance) and that you take steps to minimise the risk of fire. We'll assume you're ok with this, but you can opt-out if you wish. Hi Andres, With all things related to building it does depend on site conditions so if your house is in an area highly protected from winds then I would err towards the 1.5m level.
Its seriously draughty down there. If the existing floor covering is attractive then you may not wish to risk damaging it. 1 gaps between the floor boards will be closed with pine slivers. The joists are 7x2 with around a 16 internal gap between them. Thank you for a great article and insight to how to go about the job using different insulation materials and different methods. You have to work round any existing heating pipes running under the floor as well as getting into cramped spaces. It seems dry except after prolonged heavy rain when there is a bit of water ingress. What brand of vapour permeable membrane is needed please and what does it do? Also you need a way of pushing the rockwool into the space and then keeping it there with gravity working against you. go through identical steps outlined in this article? We look at five areas to add insulation in your home, which could help keep the heat in, lower your carbon emissions,, Get the most relevant content from Energy Saving Trust by telling us where you live. I am sure you have already opened a few windows in the warmer weather to help clear the smell. Luckily the sub floor area of our home was pretty dry to start with. The rest of the floor is above the hall. The cost of insulating a concrete floor can vary greatly, especially if the concrete is removed or additional works are done, but costs will probably start around 1,000.Insulation will make the room feel warmer in the winter and reduce heating bills by up to 70 per year. How did you go about this issue with the rigid insulation? Thanks, Hi Naz, Even good condition suspended timber floors can suffer from cold air coming through gaps in the skirting boards. A rug on the floor will help you feel warm underfoot and help block up some draughts. In practice that means there are about 5 or 6 bricks below the bottom of the joists (38-45cm or 15-18 of space). Themethod of supporting is the same whether done from above the floor or underneath. Insulating your floors is a good starting point for reducing your homes carbon emissions, and lowering your utility bills. Where the boards run the width of the room you may have to either cut the boards in half or remove the skirting to allow the boards to be lifted.
Blocking grilles or air blocks can lead to serious hazards given time, such as rotting floorboards or a build-up of carbon monoxide. How much does this insulation help: am I losing heat more to the ground or to the outside walls. If you had a continuous sheet of 100mm PIR below the joists, the U value of that board alone is 0.25. Just the information I need as I wish to insulate under my draughty ground floor. Hemp is also used in solid floor insulation in the form of hempcrete (a hemp and lime mix) which is a breathable replacement for conventional concrete. Adding an extra layer of wood should not be a problem. Thanks for your comments. Hi If you dont feel confident lifting your floorboards yourself, you can get a professional to do this as well as fit the insulation and replace the boards afterwards. If the membrane is placed above the slab an additional membrane may be required to protect the insulation from ground contaminants. If youre looking for a quick fix to a cold house, there are a lot of options available that dont cost the earth, many of which can be installed yourselves. I am keen for the maximum insulation level being achieved to minimise heat losses, and was considering using the flexible insulation detail you show above as I thought the rigid one could result in gaps where joists arent perfectly parallel or slightly unevenly spaced. Youll also have to find out which floor type you have; older houses tend to have elevated flooring (floorboards fitted across joists with a crawlspace beneath), whereas newer builds typically have a solid concrete floor. However, you can block these cold draughts from coming up through the floor use sealant or caulking to fill any gaps you may find between the floorboards and around the skirting boards. The basic idea of a suspended floor with a cavity underneath it is to allow air to circulate over the joists to remove any moisture so the joists stay dry and do not rot. My parents are having woodfibre insulation put in under a suspended timber floor but the installer has stopped the insulation at the wood paneling on the wall. Multi-foil underlays reflect heat back into the house without raising the floor height by much. Hi James, Will the space dry out over time? They had to drill additional vents but then said all was ok to go ahead. No doubt someone has come up with a good technique for using the breathable membrane from underneath; I would be delighted to hear from those with good solutions for this. One must check this Moisturebarrier.co.nz it gives us more info on this topic. In that sense there would be no building control issues as it is an approved material. Behind the wood panelling is an air gap. Ive just found this site and its extremely helpful but I could use some advice. For clarity, it is also worth stating that this was in a completely different application, as part of a complex cladding system on a high rise block of flats. Finally, the room I least want to pull the ceiling down in is actually an internal room under the lounge, with a stud wall insulated with c. 100mm of 70s(?) You must accept preferences cookies to view location-specific content. Installing too little wont give you the desired effect; too much and the floor height will rise, so door heights, skirting boards, window sills, sockets and even electrical wiring will need adjusting. I have a 1895 house with stripped boards but I need to insulate from below the kitchen/cellar/living room and dining room. I will need >50 m2 in the cellar, is there a cheaper option that is still breathable or is sheeps wool the only way to go? We were told that if there are no gaps in the floorboards and they are sealed around the edges to the skirting with silicone, and we use an underlay with a 3Tog or more rating, we should have no problems. For solid concrete floors, make sure that if they need to be replaced, your builder puts in insulation you have to insulate a floor when it is replaced in order to comply with building regulations. Why insulate? .hide-if-no-js {
I.e. The foam expands and sets into a superior, insulating layer.
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