IMPORTANT: On 1 September 2017, Celotex took the precautionary measure to temporarily suspend the supply of Celotex FR5000, Celotex CG5000, Celotex CF5000 and Celotex SL5000 while we investigate the results of recent tests (Parts 6 and 7 of British Standard 476). In addition, we have recently identified a compliance issue relating to our calculation and testing of the declared lambda value of products in the 4000 and 5000 ranges and the Crown-Bond and Crown-Fix products within the Crown Flat Roofing range. Due to this issue, the suspension of the 5000 range will continue and now includes the FI5000 and GD5000 products. Materials relating to the 5000 range products are for information only. Please note that TB4000 manufactured after 15 December 2017 will be marketed from January as Celotex TB3000 with a declared lambda value of 0.023 W/mK.

Please use the link below to read our full statement regarding declared lambda:

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Please use the link below to read our latest statement regarding Class 0:

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Over the last few months we have continued our Technical Twitter Takeover’s, featuring monthly hour long sessions dedicated to different topics affected by insulation and what we do here at Celotex. Within the Celotex Technical Centre (CTC) our fantastic team of technical advisors get asked a range of different questions so it is great to take some of those questions and explain them through a short afternoon of Twitter activity. It is also a great opportunity for those watching from across the social media stratosphere with a project enquiry to send in a Tweet using #AskCelotex to our technical team member to provide assistance.

The Celotex Floor Technical Twitter Takeover

So, February’s TTT focused on the top of your house with a pitched roof application and the topic for March was at the other end, looking at floor applications. Here are some of the questions that Celotex are asked regularly about floor applications and insulation solutions.

Question 1 – What membranes should I use in a solid ground floor with Celotex insulation?
Celotex should be positioned above a dpm and below a minimum 500 gauge polythene seperating layer.

Question 2 – What Celotex insulation board should I use for wet underfloor heating systems?
Celotex FI5000 is our specifically developed insulation board for underfloor heating applications. The increased compressive strength of the PIR insulation board provides better dimensional stability and resistance to site traffic during installation whilst the foam structure ensures better pipe clip retention. FI5000 features a composite facer with a built-in VCL eliminating the need for an additional separating layer saving time and money onsite. Just ensure the board joints are taped to maintain the VCL.

Question 3 – Which other Celotex products can be used in floor applications?
Celotex premium performance PIR insulation board FR5000 can be used in floor applications.

Question 4 – How do I work out the perimeter and area ratio?
The exposed perimeter is divided by the floor area to give you your perimeter area ratio.

Question 5 – Do I need the perimeter area ratio to assess insulation thickness for floors above ground level?
The P/A is need for ground floors only as it allows the insulating factor of the ground to be taken in to account.What Celotex products can be use din floor applications?

Question 6 – Why is a 500 gauge polythene seperating layer needed?
The layer is need to protect the foil face of a Celotex FR5000 insulation from the wet screed. In addition, the layer also serves as a VCL. However, as referenced above, latest innovation Celotex FI5000 features a built-in VCL.

Question 7 – What is the compressive strength of Celotex floor insulations?
The compressive strength of Celotex ranges from 120 kPa with Celotex TB4000 to 175 kPa with Celotex FI5000.

Question 8 – Can Celotex be used above garages or undercrofts?
Celotex can be used in all manner of floors over unheated spaces, for example concrete floors and between timber joists.

Question 9 – Should I tape the joints of the insulation in my floors?
This depends on the type of insulation used. When Celotex FI5000 is installed we would advise all joints are taped to maintain a continuous VCL. However, if a separate VCL is installed then you will not need to tape the joints. The boards always need to be tighly butted together #AskCelotex.

Question 10 – Can Celotex be used in basement floors?
Yes. Providing that the Celotex is positioned to the dry side of the tanking and is not bearing the weight of the foundations.

Question 11 – If I have acoustic insulation in between the floor joists, a cupboard then pitched roof insulation-  Will it sweat? 
Condensation should not be an issue providing the Vapour Control Layer (VCL) is installed correctly and a breather membrane or ventilated cavity is provided in line with our guidance at http://www.celotex.co.uk/applications/pitched-roof-insulation. The Celotex Technical Centre would be delighted to discuss the principles further.

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