Fire and Acoustic Door Seals

[Guest Billy]

Hello Sir/Madam,

I am wondering if you could be an assistance, I am currently working on LSE fire doors which have become a slight problem for our client, I have spoken to the Contractors Vinci to provide all the necessary information on the Dulux products used. The doors which are becoming a problem the Contractor has stated that they provided a gentle rub down and then applied the Dulux water based quick dry undercoat and Dulux water based quick dry gloss Heritage range Naples red but no primer has been used, they have stated they allowed adequate drying times between each coat which was stated as 6 hours. The problem is still occurring now could there be a chemical reaction with the original paint on the door being applied with the new paint? The Contractor states that they had painted the doors back in December 2015 and carried out touch up paint work to the affected doors in February 2016, with a drying time of 6 hours between each coat of paint, all existing door seals at this point had been left in place, they then returned in August 2016 and removed all existing doors seals and installed new doors, but the problem is still occurring and causing a problem for the client.

[Tom Sutton]

It looks like there is too many coats of paint on the intumescent seals and the paint is breaking off. I am not aware of any chemical reaction between intumescent material and paint.

Extract from BS 8214,

Decoration

Fire door leaves are generally not required to provide a specific surface spread-of-flame barrier, and may therefore be decorated as desired. There is no evidence to suggest that overpainting of intumescent seals has any detrimental effect on the ability of the seals to perform efficiently. There are some benefits in overpainting the seals as they are
less likely to absorb atmospheric moisture. However, there are limits on how much paint can be applied without there being a risk of the seal being rendered inoperative. It is recommended that overpainting be limited to a maximum of five coats of conventional oil-bound paint or varnish.

When preparing a frame for redecorating, the use of heat or chemical strippers should be avoided if intumescent seals are incorporated. If seals are damaged by either of these processes, they should be replaced in accordance with 13.3. If glazing beads have been painted with intumescent paint, it is essential that they be repainted with a similar paint.

[Tom Sutton]

Further consideration the cold smoke seal (brush) should come in contact with the door frame rebate but the intumescent seal should not and should be level with the door edge giving a 3mm gap +/- 1 mm gap. Looking at the images if the intumescent seal is touching the door frame, then it is likely to chip as the adhesion of the paint to the seal may not be as good as to the wood.