Underfloor insulation

[Astrokev]

My build thread has temporarily stalled whilst I recover from my annual holiday, and also set-to with re-decorating the house following some recent extension work, but I've been thinking...... Many builds follow the design of having some form of suspended floor, typically using joists suspended from side walls of either brick or wooden beams. Nothing wrong there, and this is the design I'll be adopting myself. However, many people include an insulation layer underneath both the telescope room and also the warm room - can anyone tell me what the real value is of having insulation beneath a wooden telescope floor? Since the floor boarding is not in contact with the ground, my feeling is that any heat loss through the floor is probably negligible and therefore not worth worrying about. Now if it was a concrete floor in direct contact with the ground I could understand it, but struggle to think what the true benefit is for a suspended wooden floor. Thoughts?? As a completely unrelated question - when posting messages I no longer seem able to do a carriage return (ie. hitting Enter has no effect at all). Not critical, but verty frustrating. Has anyone else experienced this? Is it a problem with my set-up or with SGL? This only seems to have happened recently. Thanks

[Bizibilder]

I agree with not needing to insulate under the floor - the temperature difference between out and in will be tiny and not worth providing somewhere for the mouses to live !! As to the carriage return - IE10 is the most likely culprit - MS now don't tell you when it is installed!! There is a work around if you google "IE10 Blocker" and follow the instructions:

To remove IE10:

First of all, click on the “Start” button and type “Programs and Features” in the search box. Click on the “View installed updates” in the left pane of the menu. Go over to the “Uninstall an update” screen and scroll down to the “Microsoft Windows” section. Simply select Internet Explorer 10 and click “Uninstall.” It usually takes a while until the process comes to an end, so you’re strongly recommended to avoid stopping or cancelling it. A reboot is necessary to complete the removal and restore IE9.

To run IE10 Blocker:

Click on the link http://www.microsoft...s.aspx?id=36512 to download the package and select ‘Run’ or ‘Open’. You will be asked to accept the end-user license agreement (EULA) before you gain access to the package contents. The package contains 4 different files. Pick a location where you would like to place the 4 files above by clicking on ‘Browse’. Once you have specified the location to place the extracted files, click ‘OK’. Launch an elevated Command Prompt by navigating to Start -> All Programs -> Accessories -> and then right click on “Command Prompt” and select “Run as Administrator”. Type “CD” followed by the path to where you have extracted the 4 files in step 2 above. In the Command Prompt, type “ie10_blocker.cmd /B” and hit Enter to set the blocker on the machine. You will see confirmation in the Command Prompt: “Blocking deployment of Internet Explorer 10 on the local machine. The operation completed successfully.” You can now close the Command Prompt window.

The files are in "Downloads" and this script has been run.

[Astrokev]

Thanks Roger. I think you're right! My machine (mainly use a works laptop since last weeks lightning in the South East fried my desktop PC ) installed IE10 and it also affected some work applications. I didn't think of this for SGL, so thanks for the heads up.

[Freff]

You can also use the Toggle editing mode button, (see image) this will allow you to use the carriage return. HTH.

[Gina]

No problem with Firefox.

I have insulation in the warm room floor between the joists but NOT under the scope room. The scope room wants to be at ambient temperature otherwise there will be a bigger temperature drop when you open the roof.

[r3i]

I have insulation in the warm room floor between the joists but NOT under the scope room. The scope room wants to be at ambient temperature otherwise there will be a bigger temperature drop when you open the roof.

Same here - 50mm Celotex under the warm room only. Not absolutely sure it was essential or not, but along with the insulation in the walls and ceiling, the warm room definitely retains the heat.

[Gina]

Yes, same here though not Celotex - just plain old polystyrene foam board.

[yesyes]

I've not seen a build that had the floor of the scope room insulated. As Gina said, the scope room should be as close to ambient as possible.

I will insulate my warm room all around. Loft insulation rolls have just arrived yesterday.

I was thinking for a while how I would suspend the insulation between the floor joists. I decided to use vapour barrier membrane perpendicular to the joists and suspend the insulation in that. Then add another layer of membrane on top. Then the OSB on top of that.

[Macavity]

Best avoid bridging the gap between (typically) concrete and chip/Osb? Maybe even drill a few 1" air holes in any under floor frame too? A couple of "air brick" gratings (holes with perforated metal covered?) at the ends. No matter what I do, some damp seems to creep in - But dissipates quickly with a bit of airflow.

Noe-serious Aside: I rather liked that history reenactment program "The Victorian Farm"? - To avoid the worst effects of extreme frost under a pigsty floor (keep pig trotters warm!) they laid the concrete raft over dozens of (empty!) wine bottles laid side by side...

[Digz]

No need for insulation under the scope room floor (if its a suspended floor), its not a heated space, its not built to any building regulation standards so the extra expense and complexity of detailing can be done away with. This is, of course my personal opinion.

Also, any suspended floor should really be ventilated. With the general size of DIY obsy's a single side if air bricks should be sufficient.

[BlueAstra]

My floor is patio flags under a plastic sheet and rubber mats. Since the flags were cold, condensation would form on the plastic sheet and leach up between the rubber mats. I solved it with thin polystyrene sheets, foil backed, under the rubber mats. They came from B&Q and are designed to be used under wood panel flooring.

[Freff]

I've not seen a build that had the floor of the scope room insulated. As Gina said, the scope room should be as close to ambient as possible.

I will insulate my warm room all around. Loft insulation rolls have just arrived yesterday.

I was thinking for a while how I would suspend the insulation between the floor joists. I decided to use vapour barrier membrane perpendicular to the joists and suspend the insulation in that. Then add another layer of membrane on top. Then the OSB on top of that.

Be sure to use the correct breathable membrane. With the double membrane and insulation sandwiched between timber it's going to be one heck of a moisture trap unless well ventilated, and high flow breathable membrane.

[yesyes]

Be sure to use the correct breathable membrane. With the double membrane and insulation sandwiched between timber it's going to be one heck of a moisture trap unless well ventilated, and high flow breathable membrane.

Thanks for that. I hadn't considered that. The membrane I ordered is this one:

http://www.ebay.co.uk/itm/251283897036?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649

Probably not beathable at all...

Maybe I can just cut it in strips, attach then to the joists like loops with gaps in between and put the insulation in there?

Thing is I need something to stop the insulation from just falling through the joists. What would you normally use for that?

[yesyes]

Oh, just realised this isn't my own build thread. Sorry for hijacking...

[r3i]

Thing is I need something to stop the insulation from just falling through the joists. What would you normally use for that?

I just used small sections of thinnish batten screwed into the joists at a depth to rest the Celotex sheets on and make them flush with the top of the joists. That, and also cutting the Celotex so that it was a tight fit into the space between the joists, did the job.

[Freff]

Hi Chris, I have used in the past the green nylon mesh they sell at garden centres. Its to stop the birds eating strawberries etc. Its strong, easily fixed and of course allows air passage. HTH.

[Astrokev]

Oh, just realised this isn't my own build thread. Sorry for hijacking...

Hijack away Chris. It's good to see my post get a fair bit of discussion going. It's comforting to hear that everyone who's replied is of the same opinion regarding not needing under-scope room insulation.

Chris - you say you've not seen anyone do this? Take another look around the threads; I'm sure I've seen several (mentioning no names of course).

[pmlogg]

My floor is just standard decking boards,with gaps between for ventilation, on top of 2x4 sub-frame, directly on the stone circle that's under the dome. I have one board hinged to allow access to the under-floor cabling but I've not needed to use it for the past 2 years.

The decking always feels warm to the touch, even in cold weather. No insulation needed.

[tony]

Timber has got its own bit of insulation properties to a certain degree.

The reason for my warmroom insulation is for my own comfort, and not having to wish i'd fitted it when its too late. For the price of it, it will be worth it.

I used to breed and show birds many years ago and built two birdrooms, the first wasnt insulated but the second was and the difference between them was quite noticable especially during winter.

[Digz]

IMHO the only reason to insulate under the scope room would be to help prevent moisture buildup or condensation on the timber flooring which, in the long term could lead to maintenance issues.

However this is only really a problem in 'sealed' buildings. By that I mean buildings like houses, offices, banks, retail outlets. These are all constructed with the primary purpose of keeping the wet out and the warmth in (without trying to get to philosophical about Vitruvian principles.....) and are therefore sealed. Because they are sealed structures they need a way to keep moisture under control.

In a DIY obsy the construction, (without trying to sound harsh or belittle any of the great DIY projects I have seen on this forum and the web) more often than not, it is leaky. Therefore air flows freely through the structure and moisture or condensation build up is usually not an issue.

Insulating the warm-room is a good notion and I can see the merit, just be careful of the warm-room/scope-room junction as this can be a prime area for condensation (but as said above the scope room is well ventilated so it shouldnt be an issue.)

[yesyes]

Chris - you say you've not seen anyone do this?

I should have said I don't remember seeing one ..

[Gina]

I don't remember one either

I used polystyrene foam sheets 50mm thick under the warm room floor, cut a bit oversize and wedged between the joists and noggins. No other fixing. I also used 50mm in the north wall between the damp proof membrane and the inner plywood liner. For the other walls I used 25 mm thickness, including the partition wall and door. The ceiling has 50mm between the OSB roof (covered with rubber roofing) and plywood liner. The warm room holds the warmth well in winter and I have a fan heater for winter use.

[Gina]

A post landed here that was for a different thread

[Astrokev]

I don't remember one either

In that case I must've dreamed it

[Astrokev]

Now that I've had a quick browse, I can't find one either. I think this confirms what I've suspected for a while now; that is that I'm slowly spiralling into complete mental breakdown...

Hey, interesting discussion though eh ?!