Preventing mould on bay window with internal shutters - anti mould paint?

kaboo

Hi all,
Again in need of some help while redecorating our new home.

We have bay windows in the main bedroom which have internal shutters installed on them - done be the previous residents. The windows themselves are uPVC but the shutter frame looks like its MDF or something similar - its quite light and doesnt look like uPVC to me.

There is a small gap (less than 10 mm) between the window and the shutter frame. Please see the attached pic - I have indicated this gap by a red arrow. During winters I can bet that there is condensation on the window glass that trickled down into the gap, causing water and mould damage there. I guess it was cleaned before the sale so I cannot see much mould but easy to see the marks. Also indicated with the blue arrow you can see that water made its way through the shutter frame down to the window sill.Please see the second pic and the window sill shoes some signs of water damage. I could not see signs of wood rot but wood grain/fibres swelled up and paint has peeled off. What can I do?

I was thinking to kill existing mould, dry, and seal - to minimise chances for future growth - then regular cleaning and maintenance:
1. bleach it properly and then dry thoroughly with fans and dehumidifier running.
2. fill the gap between window and shutter frame with a mould resistant acrylic sealant like Everbuild Puraflex 40 or UniBond.
3. Sand the MDF or what ever it is lightly and prime with Zinsser BIN. 
4. Sand the window sill, fill the grain with wood filler? prime with Zinsser BIN (I already have quite a bit of it from treating knotted pine panelling, plus it will seal any mould stains in the sill, plus methylated spirit which basically ethanol in BIN should help kill any residual mould ).
5. Paint with an anti mould paint. I have used Ronseal's anti mould paint on a wall earlier and have 1 L of it left. Can I use it on wood trims? I know Zinsser PermaWhite anti mould paint can be used on multiple surfaces. But could not find such information for Ronseal's.  

What would you suggest?
Cheers

NSG666

From what I gather you have recently moved into this property. If this is the case and you are getting so much condensation during these generally warmer drier months I'd be more concerned as to why. Good ventilation is essential to minimising condensation and if the house has not been properly aired for the past few years it might be worthwhile investing in a dehumidifier. Only one opinion and others will no doubt be along shortly.

kaboo

NSG666 said:

From what I gather you have recently moved into this property. If this is the case and you are getting so much condensation during these generally warmer drier months I'd be more concerned as to why. Good ventilation is essential to minimising condensation and if the house has not been properly aired for the past few years it might be worthwhile investing in a dehumidifier. Only one opinion and others will no doubt be along shortly.

Thanks NSG. The damage is not from present. No condensation at the moment. Yes you r right we bought this house recently 😀 and been fixing the niggles and decorating. I am allergic to mould spores so end up going ballistic as soon as i see any signs of it... We do have two dehumidifiers as a result... I generally do manage to keep mould low...
The question here is how can I fix the existing damage and what can i do to reduce the chances of it coming back!

Jeepers_Creepers

As NSG says, there are two issues - one is sorting out the cosmetics here, and preventing further damage, and the other is sorting out the condensation itself. There are a few threads re condensation on here, so I think we can leave that one aside for the mo'. Suffice to say, tho', you shouldn't be having any condensation during these Summer months, and shouldn't be needing a dehumidifier running.

How to sort out what you have there... It's essentially as you say - scrape, clean and sand all the affected areas to remove all loose and flaking paint, and get down to firm surfaces. You will likely end up with paint 'steps' - ie where a flake has come off, but well-fixed paint remains - that step. This will show through the new paint, so you need to feather the edges with sandpaper to blend them in.

Other than sandpaper, use scrapers, chisels, knives anything to remove thick and bumpy paint that's filled mouldings where it shouldn't. Use coarse grade paper - say 80 grit - to quickly remove and flatten surfaces, and then go finer - 120 grit - to get things smooth.

Perhaps spray some 'mould blaster' into any gaps before filling them. Allow to dry.

I can't see MDF there - the bottom frame appears to have a wood grain on the surface? MDF would be a bad choice as it would swell with water, so I'm assuming it's all timber. If there's any concerns of rot having started or threatening to, then give it all a liberal dose of wood treatment like Everbuild Lumberjack, and allow to dry.

Yes, that slot serves no purpose except to catch water! What to fill it with? I guess frame sealant or Puraflex 40 is a good bet - you want something flexible, completely waterproof and that can be overpainted. Not sure if it's worth filling in a couple of stages so's it dries more quickly? But what you definitely want is for it to be squished in there firmly so's it bonds to all the surfaces and seals them. Run your filling knife (from the other job...) along the bottom frame, using it as a guide to wipe the sealant completely flush.

Allow it to dry fully - give it a few days. If it shrinks, then apply a further skim.

If you then want to fill any gaps in the mouldings - say the corner mitres - you'd be better off there using a good quality 'decorator's caulk' as this will be easier to apply and have the excess wiped clear - not as sticky as '40', and usually water-based, so a damp cloth will clear up any excess. Again, use the filling knife to get it into the gaps, and then level it off following the profile of the moulding as usual.

Then it's the basic painting job. Bare wood - and I guess the filled areas - will need a primer. Perhaps give it a couple of coats, and then lightly sand - de-nib - before applying the top coat. Probably worth 3 top coats, as you are anticipating these areas getting wet.

Don't know what paint to recommend as there are some great ones these days. I'd consider using an exterior paint - just see what's available in the colour you want (brilliant white satin?). By the time you've finished this, there shouldn't be ANY gaps, cracks or unprotected parts where water could get through - that whole area should be 'sealed', and any condensation simply wiped up harmlessly each morning.

Ah, condensation... I think i'll try and find the threads... :-)

kaboo

Thank you thank you, really appreciate the help, this forum is awesome.

Re condensation, I haven't seen it over the last 2 months since we have moved over here. Air humidity levels in the house, measured in three different areas, are below 60%. I am jsut quite wary of humidity because of my extra finnicky nasal passage that likes to stay inflamed and respond to pollens, dust mites and mould very quickly.

Once the damage and cosmetic repairs are done, I am very confident that I will be able to deal with condensation and mould. There is no permanent solution really, just have to keep humidity and mould under control. 

Jeepers_Creepers

How to solve condensation = ventilation. (And not doing silly things that increase moisture content excessively - cooking without extraction, drying clothes inside, showering without extraction, Peloton, that sort of stuff.)

Even if it makes your room colder, it's the solution. It's obviously a balance between the two, but you want to try and rid the house of the natural build-up of moisture which takes place during the day and evening, and which is then released overnight when temps fall and the air can no longer hold on to the moisture.

It can often be as simple as - when you turn off/down your heating and go to bed, crack open all the windows in the affected rooms and let a steady through-draught occur overnight. You'll wake up to a cool - but dry - room.

Ditto with bedrooms. It's why gawd gave us duvets.

kaboo

Hello again, I am now able to come back to these windows to fix them. Have found a sealant that should help -Evostik Frame Sealant - supposed to be weatherproof, airtight, anit-mould etc etc. However, would such a sealant be removable when window frame repairs are needed - like replacing blown glazing?

Bendy_House

Looking at your current setup, if the glazing units are installed from the inside, then they don't look as though they can come out in any case, without the shutter frame first being removed.

If you do need to do work on the windows, cutting through frame sealant will be the least of your issues :-)

Reading this thread, it would make sense to me that these shutters are the cause of the condensation - they will allow warm moist air to get to the glass, but will hugely restrict the air flow to keep it dry. Do you use these shutters?

kaboo

Yeah shutters were installed from the inside and the glazing was also installed from the inside... so yes if windows frames need repairs or glazing needs to be changed then will have to take the shutter framea off!

We have been here for 2-3 months, so they are used for keeping light out and for privacy! They do look pretty but exactly how much of a nuisance they will be, in terms of causing condensation/mould, we will see in the next 6-8 months. 

I see how they could cause condensation but would they be any worse than regular curtains? This window overlooks a busy road, so any shutter/blind/curtain is likely to stay closed most of the day! 

Bendy_House

Worse than curtains? Very likely, and certainly so if they fit more snugly around their perimeter.

The windows themselves can't be left cracked open on a vent setting then, due to noise? All I can suggest is a good routine of drying the windows and surrounds thoroughly each (cold) morning, finishing off with kitchen paper to wipe up every trace, and then leave the shutters open for a while to fully ventilate the window area. Give it an occasional - weekly? - wipe over with a cloth and 'mould blaster' to keep and mould at bay - wipe it over, getting in to all the edges, wipe it again lightly to remove virtually all traces, but leaving a damp sheen of the stuff behind. It'll dry in a few minutes, but that light residue will do all the blasting it needs.

georgehere

If that gap runs up the sides as well it is a real nuisance. However, as mentioned more ventilation and reducing sources of humidity are the key. If that it is too costly then take the shutters out and re-fit them to get rid of the gap - that's the cost trade-off vs actions to improve ventilation and reduce humidity.
If you don't refit them I think the best you can do for the gap at the bottom is cover it with plastic quadrant or a flat plastic strip if the quadrant would protrude above the window frame and hit the glass.