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Panel Door Upgrade - FD20

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Panel Door Upgrade - FD20
Panel Door Upgrade - FD20 Panel Door Upgrade - FD20 Panel Door Upgrade - FD20 Panel Door Upgrade - FD20

Fire Door FUS Upgrade FD20

20 Minute Panel Fire Door Upgrade.
  • Upgrade listed or old panels doors to 20 minutes Fire Rating
  • Tested to Bristish Standards BS476 part 22
  • Product codes: FUS/FD20
Requirement check list, each door must consist of the following:
  • Minimum panel thickness 4mm
  • Minimum stiles & midrails 35 mm thick

Fire Door Fireplug FUS is designed to upgrade new or existing timber panelled doors to fire door standard. The system allows ornate and decorative doors to keep their original character and appearance, in most cases, without taking them off their hinges.

Under the action of heat the intumescent coating expands to form an insulating layer on the surface of the substrate helping to maintain the integrity of the substrate for the required period.


Tested to British Standards BS476, part 22, test No. FRI687, in April 1993 and BS476, part 20, on 14th May 1993, test No. IT360. Full reports are available on request. Six number
4mm thick pine panels achieved FD20 status in test FRI687. The pine panel was part of a Victorian panelled door with FUS applied directly onto the existing gloss paint, to the furnace side of the door.

In each test the timber surround was 30mm thick softwood and was treated with brush coats of ICT coating followed by 1 coat TSC clear top coat.


The fire door upgrade kit consists of Firefly intumescent membrane paper (ref: CFPM), intumescent coating (ref: ICT) and a topcoat (ref: TSC).

CFPM is an intumescent membrane paper 0.5mm thick, supplied 550mm wide to any length up to 100 metres long and is grey/black in colour.

ICT is a water based acrylic intumescent coating available in both a clear and a white finish.

TSC is a sealing coat to help against mechanical damage and the ingress of moisture. It provides a decorative finish and is available in a full range of colours.


Stage 1 - Primer Coat

Before FUS can be applied a sound clean surface must be attained to allow good adhesion of the system. Existing painted or varnished finishes must be carefully prepared ensuring all dirt and grease deposits are removed along with any loose flaking paint or varnish. A thorough rub down with sandpaper and a wipe over with white spirit using a clean cloth should leave a suitable surface to work with.

Stage 2 - Panels

Cut to size CFPM paper to adhere onto the panels of both sides of the door. Time and care is needed here as it is important to get the protective paper to butt against the edges of the framing styles on all sides. Once satisfied, apply a brush coat of ICT to the panel. The ICT has a thick consistency so do not overload the brush, be prepared to spread the coating, stretching it evenly over the panel. Offer the CFPM to the panel and adjust it to fit as required, there will be a certain amount of slip with the Fireplug ICT but be careful not to tear the protective paper. If adjustment is required to the position of the CFPM protective paper use the flat of the palm over as much of the panel as possible and slide the paper slowly. The second layer of CFPM can then be applied immediately. The final operation at this point is to apply two coats of ICT protective sealer over the entire surface being treated. This first coat can be carried out straight away and then left to become tacky before applying the second brush coat.

NB. CFPM protective intumescent membrane has a smoother side. If the panel is to be painted after upgrading, then we recommend adhering the rough side to the panel. Thus allowing a superior surface for decoration. Alternatively if the door is to be varnished, therefore a wood grain finish is required, either face of the CFPM can be adhered to the panel, as a wood veneer is applied directly onto the papered panel prior to the last two coats of the ICT sealer coat.

Stage 3 - Topcoat

The TSC topcoat must be applied onto a dry surface. Allow a minimum of 24 hours at normal room temperature for this. Ventilation is important to reduce the humidity of the drying area and therefore the drying time. Once dry a second coat of topcoat can be applied if humidity levels up to 90% can be expected. Two coats of topcoat are recommended should a high gloss finish be required or opacity is poor. Prior to each coat being applied a light rub down using a fine sand paper can enhance the end result.

The TSC top sealer coat is available in BS4800 colours as gloss, eggshell and matt finishes. RAL colours available. When ordering your kit please put in the comments section when at the checkout area the topcoat colour you wish.

Information on testing

The painted door application details laid out above, describe the actual procedures carried out on the tested door. A door was chosen that had soft wood panels 4mm thick and framing 30mm thick. This gives a serious problem regarding maintaining integrity in a fire, as there is very little substance to protect. It would be fair to say that the thicker the panels and framing is then the longer the door will last. Other factors detrimental to the door's possible stability and integrity were that, as a Victorian door in age it had seen various coats of paint laid one on top of the other. There was also various signs of wear and tear, corners rounded and, in places joints had split. In all the door should be a fair representation of a 'worst case' scenario.
The door edges and head were protected by FPSM surface mounted intumescent strip.

A further aspect of the FUS system is that it can be applied on site without the doors being removed making for the minimum disruption and lessening the chances of damaging what could be a valued piece of history.

FirePlug FUS door upgrading system consists of the following:

CFPM - Intumescent Membrane paper
ITC - Intumescent Base Coat (Paint)
ISC - Top Sealer Coat (Paint)

Installation Guide

1: Sand down panels and remove all grease deposits, make good any defects with Fireplug intumescent mastic. N.B. FD20
- 1No layer CFPM membrane & coatings on risk side of the door. FD30 – 2No layers CFPM membrane & coatings both sides of door.

2: Measure and cut the CFPM Membrane paper using a straight edge and a sharp knife (Stanley type) or scissors to butt tight against all panel edges. 

3: Brush apply ITC coating as adhesive to whole of the panel.

4: Carefully apply the membrane on to the coated panel, minor slip adjustment can be made while coating is wet.

5: Using a flat scraper, flatten the membrane to the panel pressing in at all edges and at each corner. Take care not to leave air pockets.

6: Apply 2No coats Fireplug ITC to the whole leaf to
ensure a uniform decorative finish.

7: Stand aside and leave 24hrs to allow ITC coating to dry hard.

8: Apply Fireplug TSC (top sealer coat) to whole door and leave 24hrs to dry. N.B. 1No coat is enough to seal the system.
Test Report No FR1687: To BS476 PT22 & Test Report No IT360: To BS476 PT20


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