Ventilation in old house

DougB

I have a holiday home in Kerry close to the ocean. When we are not at the house, the heat is on a timer for a couple hours at night, and I run a dehumidifier upstairs. I know ventilation is important for a damp house. The fireplace helps with that downstairs.

The attic has a 14"x14" access "door" (its just a piece of plywood lying on top of the opening), and I was wondering if I should open that door a couple inches to improve ventilation upstairs. There is a lot of wind getting into the attic, and when I open the door on a windy day, the wind seems to be pouring into the house, so I have been keeping it closed.

Anyone have advice?

Thanks

Joe1919

I have a approx 100 year old 2 story (semi), so am interested in your post. I have also looked after other old houses for people.The house is generally dry upstairs but a little damp downstairs especially under windows as no damp proof. This year, I had a slight problem with mildew on one wall but I reckon its caused by condensation and cheap emulsion and hope to correct by using a mildew resistance paint.
Anyhow, as far as I gather, these houses were originally well ventilated because they had loose fitting windows and doors, along with plenty of chimneys. However, fitting pvc windows and doors reduces this a lot. I fitted one vent (4 inch pipe) in one problem area. This is a bit of a job with 20 inch rubble walls.

As regard heat and leaving the attic open, I would be careful. The one thing you want to avoid is causing a warm spot downstairs that will drive warm moist air upstairs into colder rooms and into attic/roof space where condensation will occur. I have seen old houses doing relatively ok with no heat and just ventilation (windows left slightly open where possible & upstairs etc.) Make sure roof and down pipes are not leaking.

There may be some additional local problems e.g. Moist air blowing in from sea etc, so it would be good to talk to locals about this.

But I would be interested in yours and others experience.

DougB

Thanks, Joe 1919. I did have new PVC windows fitted over the last two years, with a couple more to go yet, hence my concern about ventilation. The two old wooden doors let a good bit of air in. Since the house is near the ocean and very exposed to weather, I cannot leave the windows open to any extent at all when we are not at the house.

The house is c. 1935, with a c. 1960 addition in the back. Many of the interior walls are dry-lined, but the ones that aren't show the effects of damp - bubbling, peeling paint etc. I am assuming that this is from the cold/damp house over the winter. For the walls that are not dry-lined, I periodically scrape the affected areas, apply a Damp Seal undercoat, and then re-paint. That holds up for a couple years.

The heat is on for only an hour or so in the winter months if it is very cold. When we stay there at other times, the house dries out well when we open up the windows in the day and the put the heat for longer periods, as needed. But there is always a bit of a damp smell throughout, so its not just the peeling paint that is an issue.

So, the plan was to open the attic door a couple inches to improve ventilation/air circulation in the winter, and close it up when we are there with the heating on.

Joe1919

The fact that paint is bubbling would seem to indicate that moisture is trapped in the wall and trying to get out. Sealing the walls may not be the thing to do here. It may be better to let them 'breath'. I still have all the lime plasters on the inside of my old house (except in a small area where some patching up was done) and have avoided using gypsum and sealers . I have only used dry lining sparingly.

It may be better when dry lining these houses not to insulate or use foil back board and leave small air gaps. Gypsum plasterboard has some breathable qualities without these. Also remove old wall papers and oil paints behind plasterboard if possible as these encourage mould growth and make wall less breathable.

It is always considered better to ventilate the house directly outside from the source of moisture (usually downstairs). It is never recommended to vent into the attic.(afaik) If ever replacing windows, get ones with some type of built in vents.

Having said all the above, I am not an expert and there are different and conflicting opinions out there.

DougB

Thanks, I appreciate your ideas, especially on the attic ventilation.