Is there any point going with vents in windows, instead of the traditional vent in wa

k123456

Our house will undergo extensive renovation, new extension shortly

Is there any point going with vents in windows, instead of the traditional vent in wall

Surely it is cheaper for vents in walls,

Would be interested to hear the pros and cons of each

Thanks

Ps is there any reason to have both vent types

fclauson

have you thought of dispensing with both and putting in a MHRV ?

kieranhr

HRV obviously much better, but sometimes too disruptive for a renovation. Whichever vents you install, make sure they are properly sealable. If they aren't, and they start whistling at you in the winter, chances are they'll be getting stuffed with newspaper later. Window trickle vents are usually better sealed than wall vents, though I've seen some flimsy trickle vents too.

fclauson

why would you want to seal them?

Part F is very clear that what "unblocked" ventilation limits you need

If you fail to ventilate and you start to insulate more you WILL get mould - the more passive/part L 2011 you are the more likely you will get mould with incorrect ventilation

kieranhr

I'll leave aside the merits of a set of Building regulations that tell you (through the ACDs) to seal up all window and door opes with flexible sealant, and then tell you through a four-year old Part F document to drill a four-inch diameter hole through your wall for ventilation. That's a whole other conversation.

My approach to ventilation is one of personal responsibility for the homeowner. If you need fresh air, there are windows and vents provided that you can open. If you don't, you can close that window or vent again.

Obviously HRV is the ideal solution where it's feasible/affordable for the client. After that I would personally recommend humidity-controlled vents, though they aren't cheap either, at around €95 each for the kit.

sydthebeat

the 2009 TGD F allow for "background ventilators" which are closable.

i suppose the regs assume people will be educated enough to know to reopen the vents after closing them... but ive seen houses where window grills have NEVER been opened.

daver123

k123456 wrote: »

Our house will undergo extensive renovation, new extension shortly

Is there any point going with vents in windows, instead of the traditional vent in wall

Surely it is cheaper for vents in walls,

Would be interested to hear the pros and cons of each

Thanks

Ps is there any reason to have both vent types

I hav trickle vents on the windows i got and they are spot on. All the rooms have plenty of fresh air in them. If it is a bit noisy out on the road some night it is easy to close them off. The odd time when the wind is strong and cold from a certain direction i would close them in that room for a few days till the wind died down. The trickle vents also help against condensation forming on windows in cold / damp weather.

fclauson

kieranhr wrote: »

I'll leave aside the merits of a set of Building regulations that tell you (through the ACDs) to seal up all window and door opes with flexible sealant, and then tell you through a four-year old Part F document to drill a four-inch diameter hole through your wall for ventilation. That's a whole other conversation.

Agree - but people are missing the point on ventilation - my local school had their walls pumped - but failed to up the ventilation back to part F requirements

they now have some of the best mould I have ever seen growing inside a building - which will do wonder for asthma etc (they have now corrected this problem thank goodness) :eek:

daver123 wrote: »

I hav trickle vents on the windows i got and they are spot on. All the rooms have plenty of fresh air in them. If it is a bit noisy out on the road some night it is easy to close them off. The odd time when the wind is strong and cold from a certain direction i would close them in that room for a few days till the wind died down. The trickle vents also help against condensation forming on windows in cold / damp weather.

In a well insulated house but non cold bridge free house condensation on the windows is a MAJOR WARNING that you will have condensation on other cold bridges - which you might not see because they are out of site (behind dry lining, or in corners behind cupboards)

Doop

In my opinion window trickle vents are not enough ventilation for a bedroom. Currently living in a 3 bed timber framed house with only trickle vents in bedrooms. The house is heated to quite a high standard, mornings and evenings. I throw open the bedroom window every morning, yet every bedroom has mold growth to some extent, while it may be minor it is still an annoyance. Much easier to fit hit and miss vents during construction then trying to retro-fit.

kieranhr

One question Doop - where specifically in the bedrooms is there mould growth? This may be more indicative of cold-bridging than poor ventilation.

Usually a single trickle vent isn't sufficient for a bedroom. You may need two or three to get up to the required 7000 mm2. Fortunately it's fairly easy to retrofit extra trickle vents.

Doop

There is two openable sections of the window both with trickle vents which are open permanently.

The mould growth is localised on the edge of the ceiling furthest away from the window more around the area of a partition wall between rooms, not the gable wall. Its directly over the bed so I always assumed it was condensation over night building up in this area of the room, which is furthest away from the ventilation.

Although that said the other double room had a much worse case of it which was again on the ceiling but directly over the window.

kieranhr

Interesting. My first guess would have been window reveal or wallplate cold-bridge but that's obviously not the case if it's on an internal wall. And two trickle vents should be adequate, unless they are very small or blocked. I'm intrigued now.

Can we assume that the one around the partition wall is removed from the main cross-flow ventilation route, which would run from the window to the bedroom door? Also, I wonder if the attic insulation is a bit light. Is it a flat ceiling with fibre insulation between ceiling joists over? There should ideally be 300 mm of insulation here if so.