Attic Floor replacement / wood shrinkage?

[PetePontoValentino]

I am about to replace 75 m2 of attic floor in my renovation project. The house has not been occupied for a few years and has no insulation at all. I want to replace the floor before insulating the attic ceiling (as I would like something to stand on that might take my weight).

The floorboard I am seeing in the shops contains about 20% moisture so will probably shrink as it dries. Logic says I should leave it for some time in the house before using it. I am not sure this will solve the problem as the ambient temperature of the house will increase when it is insulated.

Thoughts??

 

[sammy.se]

I find that the green looking tongue and groove chipboard typically used for flooring nowadays, is stable, you can just crack on with it.

What kind of flooring were you considering?

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[PetePontoValentino]

I find that the green looking tongue and groove chipboard typically used for flooring nowadays, is stable, you can just crack on with it.

What kind of flooring were you considering?

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I am currently looking at a Douglas Fir T&G. Part of my problem is that I am based in Switzerland so all of the info is in German. This is the one https://www.bauhaus.ch/de/rauspund-douglasie-20833897

 

[sammy.se]

Ah I see.
This is the closest I could find to what I meant:

https://www.bauhaus.ch/de/osb-verlegepl ... m-14615068

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[PetePontoValentino]

Thanks, could be an option. I would want to eventually cover it but that could be a good first step (and is about half the price of my original plan

 

[AJB Temple]

Words of advice, from experience. If you are renovating the whole house, make sure you have got any loft area re-wiring and plumbing in before you lay flooring. If I am laying over cables etc (as opposed to running through surface trunking) I prefer NOT to use tongue and groove boards as they are a right pain to lift again.

You may find it a great deal more thermally efficient to insulate beneath the attic flooring rather than insulating the roof - especially if you have plenty of head height.

I have a place in Mannerdorf and when that was built, the Swiss designed basically a cold roof (though with some insulation) and a hell of a lot of insulation between the top floor ceiling and the attic floor.

 

[PetePontoValentino]

A small world. I used to live in Uetikon am See and Mannedorf. We are now in Wädenswil just over the pond.

The house is a 1895 tessinerhaus. It needs a lot of work, so, whilst I would like to avoid rework my current focus is on stabilizing the building. I also want to ensure it is usable by the winter. We now have a safety certificate for old wiring but I want to replace the lot (and add network cabling etc.). We're also doing crazy things like painting the interior to make it usable knowing we will need to embed cabling in the walls and re-paint later. I guess part of the approach is that we have accepted this will be a 3 to 4 year project and some stuff we want to do (solar panels / commercial kitchen) will need to come later due to cost reasons.

The discussion here so far has helped my thought process a bit (also focussing on real objectives). One of the other guys suggested using sheets like this https://www.bauhaus.ch/de/osb-verlegepl ... m-14615068 as an option that is less prone to shrinkage. I initially rejected the idea because of how it looks. In reality I need to get rid of the rotten boards asap and replace them with something more usable. This could be a good first step, especially as there will be some rework. I can then finish off with some cosmetic stuff later.

I want to use the attic space as a living area / home cinema so my tendency is to insulate between the rafters and plasterboard over it later.

Thank you for helping my thought process

 

[sammy.se]

I agree about lifting the floorboards up. It's a real pain and the tongue and groove always breaks on the first couple you lift off (if it's fitted tight)

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[AJB Temple]

Good luck with the project. My place is rented out currently but I will retire there eventually. Commercial kitchen sounds intriguing, tell us more!

 

[PetePontoValentino]

Thanks,

It is an old house with 6 bedrooms and there is a cottage in the garden (which has been used as a shed). Our plan is to do the renovations to a good enough standard to open a B&B in a few years. Fitting the kitchen out will be one of the last steps. We intend to install something between a domestic and commercial one. I would love an Aga (been there and done that). We also would like a dishwasher that actually cleans dishes (I have seen a brand called Hobart used over here. Stainless steel and often used in Cafe's and Bar's... I guess that gives an idea of where we are heading

Pete

 

[AJB Temple]

Hi Pete. Yes, Hobart are well known in the catering trade for dishwashers, mixers etc. I think they are made in Germany.

Having had a few Agas myself I would suggest that are unsuitable for commercial use as the heat loss when the lids are up too much or the ovens opened a lot, means that they are too slow for commercial cooking, though if you are only doing say a dozen breakfasts, it would be fine. The whole industry is gradually moving over to induction for hobs as far as I can see, although many of the commercial heavy duty ones are 3 phase.

 

[PetePontoValentino]

An Aga is certainly a candidate as the house has no heating at all. Looking at the current offering some of the newer ones have integrated induction hobs so a good compromise. Our direction is semi-commercial rather than full on as we will have 8 to 10 guests max.

For the floor we make progress. I lifted some of the "rotten" boards a week ago and found the problem to be wildlife rather than rot. Last week a bloke from an extermination company visited. His assessment was that the culprits have long since gone (on the basis that the roof has suffered no damage at all.. so we proceed.

I am about to order T&G for the job. I am going this way as it is probably easier to lay as I am relatively inexperienced. Also, as the plasterboard ceilings in the top floor are shot and need replacing we can deal with cabling and plumbing from below.

My next question; the reason for lifting the boards last week was to measure the space between joists. The supplier I planned to use recommended I use at least 23 mm boards if the gap between joists is more than 60 cm. I measured 80 cm! Going back to the supplier they now recommend 27 mm which is the thickest product they do. Because I am a bit of a cynic, I find myself questioning the recommendation.

I have just measured the old boards and they are 34 mm and am trying to decide what to do (beaning in mind that the old wood is probably original and is very unevenly cut. I guess it comes from an era when manufacturing techniques where very different and the mechanics of this stuff less understood. Is there a formula people use for calculating the required thickness of floorboards in relation to thickness and joist gaps?

 

[spb]

Not a formula, but the rule of thumb I've learnt is 18mm for 400 centres and 22mm for 600. Extrapolating from there would make 27mm for 800 centres seem pretty reasonable.

 

[PetePontoValentino]

Thanks SPB,

it also seems 27cm it the thickest readily available here in Switzerland which kind of helps the decision process.

Pete

 

[PetePontoValentino]

So, the floor saga is finally moving forward. We've found an outfit that comes close to what I would call a "proper" builders yard in Switzerland (https://www.reguscireco.ch/).

We visited their Biasca store and enquired about what they can offer and the range is vast (thicknesses, widths and lengths) and all sizes in pine and larch.

After previous experience I asked about delivery lead times and was pleasantly surprised when the guy looked at his watch, shrugged his shoulders and said "we will struggle to deliver today so it'll have to be tomorrow".

We will go to their larger Bellinzona store on friday so we can look and decide what then order for "next day" during our next visit to the house. Fantastic!

Also, having discussed the project with a friend who has done similar projects I am going to do things slightly differently. I will move the badly damaged boards and patch with ply sheet then lay a "floating floor" on top. He says it will retail the structural integrity of the floor and give us much better sound insulation. Basically there will be some matting between the two floors and a gap between the new boards and the structure of the house. It will be much easier to lay too.

Thank you all for your pointers on this journey so far!