I think the main debate would be over whether this is more or less airtight than a rigid board material which is gap filled with expanding foam and then taped. Will the space dry out over time? 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. Any help would be very appreciated. So the choice of material does actually make a big difference, and buying premium at 1oomm thickness is not at the point of diminished returns. A suspended timber floor tends to be cold and draughty because of the air circulating beneath it. Kind regards I would suggest to speak to your local council before you do this. A brilliant piece of content with some common questions answered! Heat Loss Prevention – Underfloor insulation helps a house retain heat appose to actual warming a house directly. Your article is really interesting but unfortunately I’m still unsure how best to go about insulating the floor! If you do it from under the floor use mineral wool. Energy Saving Trust. One of the easiest and least disruptive ways to insulate your floor is to install an ultra-thin insulating underlay or polyfoam board directly beneath your carpet. or there is a sufficient gap under the joists to use the crawl space to actually crawl. I’d like to make a couple of technical points to add to the description above, to help make the choice between different insulation materials. Website Terms of Use * Contact UsCopyright © 2021 Great Home, Replacement Boiler Cost Online Calculator. We have used the old floorboards to support the PIR insulation board 90mm thick.. I have not spotted any reports in regard to fire in domestic houses or bungalows associated with PIR, despite its widespread use. Contractor came back saying that can’t install insulation under kitchen if cabinets in place, or bathroom because it is tiled. On your question on thermal foil stapled to the bottom of the joists I’m afraid I haven’t got a particular view. Insulating a Suspended Timber Floor. Hi After reading this article 3 times I have asked for pro advice my local guy and the main problem is not the U-value, but draughts. It is therefore advisable to always insulate 100% of the floor. Assuming that you want to sort the issue permanently and reduce your heating bills there are two main methods of applying insulation: Removing existing floorboards can be very hard work and risks damaging the boards themselves. If you do not have any air bricks supplying ventilation to the void below your floor, these will need to be added at the same time as the insulation and professional advice should be obtained on the appropriate location and number of these. 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. Hi Having more rather than fewer vents will move the moist air faster so should reduce damp. I can do a bit of DIY and trade-people are scarce or notoriously unreliable in our area so I am looking at doing something basic myself to damp the noise if you can advise. #CraftedForLife. This website seeks to help those searching for the basics about improving their home. A damp board could curve up and damage the UFH pipes and the screed. For those undertaking it on their own homes it is more a judgement on which material is easier to work with and will take least time rather than simply material cost. Best suited for older properties that have suspended timber floors in which you can access the crawl space, suspended timber floor insulation lets you fill the cracks and gaps around the wooden panelling with mineral wool insulation. As there will be less cold air infiltration into the house itself, there is the potential for less ventilation in some areas of the home. Or would this somehow lead to damp? The rest of the floor is above the hall. Insulating under the floorboards on the ground floor will save you about £40 a year. You have to work round any existing heating pipes running under the floor as well as getting into cramped spaces. Adding a layer of Spray foam insulation under the floor can prevent moisture from soaking the wood floor. Keep in mind that foam spray gives off harmful fumes during installation. See See Insulating A Suspended Timber Floor From Above Floor. If the work is being done from underneath then the insulation can be held in place with either tongue and groove boards or with a vapour permeable membrane. Electrical cables should not run thought the insulation and gas pipes should also not be insulated. One must check this Moisturebarrier.co.nz it gives us more info on this topic. Useful discussion. Halls are generally the coolest place in the house so air can hold less water vapour. Green Homes Grant Salford The problem we have is the underside of the boards supporting the insulation is damp. Maybe another commenter with more expertise in this area would be able to offer further insight. Properly insulating your floor will not only warm your feet, it will also help you to save money. If your house has a suspended timber floor on the ground floor, then a layer of insulation can be held in place under the floor between the joists. The gap beneath a suspended floor should always be well ventilated, and this becomes particularly important when you insulate the floor. There are certainly other options for applying insulation. as crawl space is very limited i have lifted most of the floor up and have fitted battens. Everywhere else I read tells me to fit a VCL on top, but your diagram for fitting from underneath does not show one. Green Homes Grant Bolton My questions are the periscope vents as good and will enough air flow. The combination of cold air through the floors and hot air out of gaps in a loft hatch can lose heat very quickly. Without going through all the numbers, the very high cost of PIR board is very hard to justify if it is being bypassed like this. I haven’t written anything about condensation in halls but see a piece on condensation in roofs which highlights some of the same issues: https://great-home.co.uk/condensation-in-roofs/ Conventional foil-faced, impervious (non-breathable) PIR/PUR boards are commonly used in suspended floor upgrades and this can provide some thermal performance benefits, in the short term at least. It’s hard for me to say what the airflow characteristics of your own space will be but most houses perform well to the above guidance. This leaves your home draughty and uncomfortable, while you waste energy and money heating cold rooms. (if they share the same timberwork then it may explain why the footsteps carry on the ground and second floors) And would I be better off sealing gaps in the floorboards with decorator’s filler? They are available in lots of different densities, the heavier ones are designed to have more noise absorbing ability, and are also fireproof (unlike PU or PS). As you say, the simplest way is to batten out the joists and fit rigid insulating board. Green Homes Grant | Floor insulation (for a... You should use an approved professional installer to fit suspended floor insulation. 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. The boards are faced both sides with aluminium-foil to form a vapour control barrier to stop damp. 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. This is also a job I’m thinking to do soon. Before considering whether to add insulation, it is important that there is adequate cross-ventilation in the sub floor to remove any potential for damp and to keep the area dry. 1 gaps between the floor boards will be closed with pine slivers. insulate from under the floor using the crawl space underneath. Also big thank you to Miles for pointing out issue of thermal bridging through the joists was bugging me for some time. Suspended floor insulation is very useful in strengthening the foundation of your floors as they add support between joists meaning you should expect a sturdier floor in the long run. On this basis I wouldn’t recommend it. Many older houses with suspended timber floors in the UK have big draughts and inadequate floor insulation; this can cause cold feet as well as higher energy bills. As much as 15% of the heat in a room can be lost through uninsulated ground floors. home was raised some time before we bought it. If you are in a very old property with a high risk of damp then often sheepswool rather than rockwool is used; although it is much more expensive it provides better insulation when exposed to extreme moisture. 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. Thank you for a great article and insight to how to go about the job using different insulation materials and different methods. Underfloor Insulation Of Suspended Timber Floors - Great Home Also FYI Kingspan can be installed only when you lift the floor than finish with foam (tones of it if the floor is not even, fire proof pink foam). Actis insulation make great products as an alternative to traditional pir and wool products and a lot easier to use. This article is really helped me a lot. Your 14″ depth of the space beneath the floor sounds pretty typical and for this depth the advice is that vents should be spaced every 1.5-2m around the outside wall. If it’s sealed up well would this provide any benefit? Q-Bot uses robots to spray insulation under the floor with minimal disruption to your life. Before carrying out any work, a thorough inspection of all the joists and underfloor timbers should be carried out by an approved professional for signs of damp, rot or insect damage, and appropriate repairs carried out if required. First off thanks for making the site and the guide as its a job that i am looking to do in the near future. 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. Is there a risk of condensation and damp? Installing under floor insulation can address both these problems. to the joists. Your email address will not be published. There are several different insulation materials and products which can be used, including mineral wool, rigid boards and foam and professional advice should be obtained on the appropriate thickness of each of these to be installed in your home. I am in the process of carpeting the insides of my cupboards to try and stop the noise! Installing underfloor insulation can address both these problems and give a payback on your investment. Available at. Selecting the right material is a balance between: An  U-value is a measure of the thermal insulation of a material with lower U-values being more effective insulators. Process of installing underfloor heating on a suspended timber floor In this section we look the installation process for a wet underfloor heating system, although in practice you could also install an electric ‘dry’ system. As we had the original oak floorboards in the hall and Amtico vinyl in the kitchen and utility area there was no real option of removing the floorboards. The moisture is likely to be a combination of slightly less ventilation in the hall and water vapour from some of the activities you describe. Hope this helps and all the best with your project. Original wooden boards will go back on top and large gaps between the boards closed with pine sleepovers. It offers an independent view, trying to balance the interests of … read more, * Cookie & Privacy Policy * Use in this high rise flat application is quite rightly no longer permitted. In that sense there would be no building control issues as it is an approved material. This is extra activity and cost. Mineral wool insulation comes in roll or batts (slab form). 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. Save my name, email, and website in this browser for the next time I comment. I am now considering a 60mm PIR board and topping it with rockwool. (function( timeout ) { This is a very useful article as thinking about doing this in our house. Could it be the mineral wool touching the wooden boards that’s causing the damp? Hope this helps. we have just brought a 1930s ex council house and i want to fit insulation under the ground floor floorboards. Green Homes Grant Bury This will not be a problem unless you have existing damp issues in the floor or if you do not have adequate ventilation under the floor. Energy Efficient Homes: Eco Houses, Zero Carbon Homes, Passivhaus & EnerPHit, Mechanical Ventilation Heat Recovery Systems (MVHR) Explained, Using Robotics for Underfloor Insulation of Suspended Timber Floors, Underfloor Insulation Of Suspended Timber Floors, Insulating A Suspended Timber Floor From Above Floor, Insulating A Suspended Timber Floor From Underneath The Floor, Solar Battery Calculator: Likely Bill Savings. Where you are fighting lack of underfloor ventilation and the lack of a DPC then this could be the best option. By insulating above the suspended floor you have reduced the heat loss through the suspended floor. Installing any amount of insulation will warm the floorboards and go a long way towards eliminating draughts. Whatever material is used it is important to examine the underfloor area for damp and address these before insulating. They used chip board on brick piles for the new floor.. All joists should be checked to ensure they are dry i.e. Green Home Grants Blackpool, Contact Us Missing out these areas will cause a cold strip at the floor perimeter which can again become a condensation risk, especially as corners are always the coldest parts of rooms. You may want to consider doing this at a time when the room is empty for other reasons, such as when you are replacing the carpet, fitting a new kitchen etc. Nice article, installing underfloor insulation may not be very cost effective or save you money in the long run, but it is certainly very comfortable for people living in the house. 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.