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Housing - Renovation: Insulated loft hatch - any tips?

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    • CommentAuthorrhamdu
    • CommentTimeNov 30th 2011
     
    I need to construct a loft hatch which is safe, neat-looking, well insulated (at least 100mm PIR) and reasonably vapour-tight (it's over a bathroom). It does not have to include a loft ladder.

    I'm currently thinking in terms of a slab of PIR encased in plywood. The edge opposite the hinges would be bevelled so that the 100mm+ thick door opens cleanly and closes tightly. The whole thing would close upwards onto a doorstop bead fitted with a draught seal.

    Any alternative ideas or design tips welcome. Is there a standard way to do this job? What kind of hinges and catch would be best?
    •  
      CommentAuthorJSHarris
    • CommentTimeNov 30th 2011 edited
     
    I've no idea if there's a standard way, but what I did for a loft hatch just outside my bathroom door, with a loft ladder (so the hatch is hinged, with a catch to hold it up) was fit two layers of 50mm PIR (which is what I had to hand).

    I cut the edges of the foam so that it was tapered very slightly, enough to allow the top of the foam to slot in to the hatch opening easily, with the bottom of the foam (the bit attached to the hatch) a very snug fit in the hole. I then stuck some 25mm wide, 3mm thick neoprene foam (the self adhesive stuff) to the tapered edge, maybe 20mm up from the hatch upper face. To stop this coming free as it's slid (tightly) into the opening I stuck shiny parcel tape over it, overlapping it down to the hatch face.

    This seems to work well and seems to have reduced the condensation I was getting on the sarking, although we've only had a couple of cold nights so far, so I'm not wholly certain yet. The hatch is a tight fit into the opening all the way around, and the gap around the edge is effectively sealed with the foam. The catch that normally holds the hatch up ensure it stays in place.

    One thing to watch is draughts lifting it. After I sealed mine I had to adjust the catch to hold it in place more securely, as being sealed it was now responding to wind outside by banging up and down (something it never used to do).
    • CommentAuthorskyewright
    • CommentTimeNov 30th 2011
     
    My approach was a double hatch...

    Using boards I extended the frame of the hatch so that it was in effect a short tunnel. Around the top edge of the tunnel I placed weather strip. I then constructed a well insulated oversize "lid" that sits on top of the tunnel. At the bottom of the tunnel (i.e. at room ceiling level) there is a hinged hatch as normal (but with more insulation, of course).

    That's a simplified description, but hopefully enough to give the general idea...
    • CommentAuthortony
    • CommentTimeNov 30th 2011
     
    I made a double hatch too

    how about an "off the shelf" one at ceiling level then another home made one at top of joist level? all air tight and insulated to the same degree as the ceiling?
    •  
      CommentAuthorDamonHD
    • CommentTimeNov 30th 2011
     
    My effort is much more crude: about 50mm or less EPS glued to the back of the existing plywood hatch cover (though actually there's an off-cut of my aerogel plasterboard in there too), and some draught-stripping around the hatch. All waste or packing 'upcycled'!

    Rgds

    Damon
    • CommentAuthorrhamdu
    • CommentTimeNov 30th 2011
     
    Thanks for all those ideas, and particularly the suggestions with a double hatch. The loft is used for storage and we don't want a big fat insulated door hanging down and partly blocking the hole through which we have to poke a ladder and then lift suitcases etc.
    • CommentAuthorwookey
    • CommentTimeDec 1st 2011 edited
     
    Here's mine:
    thread: http://www.navitron.org.uk/forum/index.php/topic,5110.msg54952.html#msg54952
    pic only: http://wookware.org/pics/house/lofthatch.jpg

    hatch+EPS (I'd use PIR these days), with bevelled end. EPS covered in hardboard. Foam seals along stop edge at top and above hinge.

    Things I'd change if doing it again: Arrange a lip at the bottom so you can seal it there. With the seal at the top, wet air gets up the sides then condenses on the very cold timber near the top. I also didn't seal the EPS/hardboard so it collected quite large amounts of condensed water.

    I painted the sides gloss and sealed up all the gaps so that now the condensation that happens doesn't soak in. We'll see how that goes this winter.

    As you realise, a fat insulated door gets in the way unless you have a way to hold it back. I put a clip on the ceiling to do that and hold it in the position in the pic.

    Double hatch is a good idea, but I can't think of how to make it work with the loft-ladder (hatch has to open down), but there may be a way.
    • CommentAuthortony
    • CommentTimeDec 1st 2011
     
    I cant see any draught seals?

    Mine has them on both hatches.
    • CommentAuthorrhamdu
    • CommentTimeDec 1st 2011
     
    Nice pic, Wookey, that is my imagined hatch on steroids - and very neatly constructed, too.

    Like you I figured to put the draught seal at the top, but it's clearly a better idea to have it on the 'warm' side of the hatch.

    For anyone else planning an insulated hatch, a good starting material might be that flat roofing board, made of foilback PIR insulation board bonded to 3mm plywood. We've got it in our flat roof (unsurprisingly) and also as over-the-joists insulation in the lofts. It's strong enough to walk on, and better insulation than the EPS loft boards they sell in B&Q. Sadly we have no offcuts big enough to make a hatch.
    • CommentAuthorwookey
    • CommentTimeDec 1st 2011
     
    Tony, yes that pic was taken before draught seals were added (and later the sides painted). The seals are (now) along the bottom of the whitish/spotty piece at the top of the hatch-hole.
    • CommentAuthortony
    • CommentTimeDec 1st 2011
     
    Oh OK sorry :shamed:
    • CommentAuthorborpin
    • CommentTimeDec 7th 2011
     
    I have been thinking about this too and wondered if it would be OTT to buy a window without glazing and fill the middle with insulation instead. Other than that I have not found a satisfactory solution (other than warm roof of course):bigsmile:
    •  
      CommentAuthorSteamyTea
    • CommentTimeDec 8th 2011
     
    Posted By: borpinI have been thinking about this too and wondered if it would be OTT to buy a window without glazing and fill the middle with insulation instead

    Put a triple glazed unit in, and one in the roof and take the lightbulb out on the landing, will work well till it is dark, but what a talking point. :bigsmile:
    •  
      CommentAuthorJSHarris
    • CommentTimeDec 8th 2011
     
    <blockquote><cite>Posted By: borpin</cite>I have been thinking about this too and wondered if it would be OTT to buy a window without glazing and fill the middle with insulation instead. Other than that I have not found a satisfactory solution (other than warm roof of course)</blockquote>

    If you have a nearby UPVC window manufacturer, then you may well find that if you pop in and ask they will weld up a simple frame for you from some of their standard sections. A friend did this to make a very non-standard access into and underfloor crawl space years ago. I'm pretty sure he said it was pretty cheap, as it came up in a conversation about the high price of replacement windows.
    • CommentAuthortony
    • CommentTimeDec 8th 2011
     
    I would rather that you bought an off the shelf module than used a window, a miss-measure may be not a new one and not at all in my book

    Make one with wood and insulation.
    • CommentAuthorchuckey
    • CommentTimeDec 8th 2011
     
    I am getting involved with this job, word of warning if you have or intend to have a loft ladder, hinge the hatch cover at right angles to the ladder else there is a conflict of insulation and ladder at the ladder's mounting point. Grrr :-( , that why I am doing it!!
    Frank
  17.  
    Avoid the use of hinges, you can then move the hatch completely out of the way and you get a consistent fitting on all 4 lips/sides.
    Anything that lets light and extra air flow when wanted has gotta be worth thinking about.
    If you combine the double feature you could go for a 2 season option.
    Lying in the bath with a skylight must have some benefits.
    cheers
    Tom
    •  
      CommentAuthorDamonHD
    • CommentTimeDec 8th 2011
     
    I had an interesting experience with the skylight above my bath in a flat on the Royal Mile in Edinburgh; hail used to be able to make its way somehow around the edge, resulting in being hailed on in a hot bath! Not sure what the benefit was in that case...

    Rgds

    Damon
  19.  
    A genuine unique experience - surely as a conversation it's filled a moment or two. Similar to swimming in the rain I expect and I enjoyed that very much.
    • CommentAuthoran02ew
    • CommentTimeDec 9th 2011
     
    Use a cheap 3G window from russel timber tech. You hav a good insulation, nicely airtight and any size you like

    Cover the glass with a nice picture of the sky?
    • CommentAuthortony
    • CommentTimeDec 9th 2011
     
    Depend what you call good insulation and compared to what.

    My loft insulation is 0.09, hatch estimated as 0.2, the best window will only be 0.7 which is poor in comparison

    Aim for as close as you can to the level of insulation in the loft
    •  
      CommentAuthorSteamyTea
    • CommentTimeDec 9th 2011
     
    Posted By: DamonHDNot sure what the benefit was in that case...


    Flagellation, it is good for the soul, maybe. Did you feel spiritually nourished after.
    Or
    You knew it was hailing :bigsmile:

    I used to manufacture and fit saunas, steamrooms, spabaths and sunbeds, nothing surprises me now (except the Sheffield YMCA spabath) :shocked:
    •  
      CommentAuthorJSHarris
    • CommentTimeDec 15th 2011
     
    Interesting to see that there was an ad for just such a beast as this in the flyer that dropped out of the issue of Green Building magazine that popped through my door today. Looks to be a neat job to me, more details here: http://www.ecologicalbuildingsystems.com/workspace/downloads/Dolle-Profi-Plus-Attic-Hatch.pdf

    It might be a bit pricey and the U value could be a bit lower, but might be a good solution for a new build.
    • CommentAuthorwookey
    • CommentTimeDec 16th 2011
     
    It says the insulation is 70mm thick but it really doesn't look it - it looks like about 30-40mm. U=0.77 is a lot better than your average roof hatch, but a bit feeble for one purpose designed to be 'good'.
    •  
      CommentAuthorJustin
    • CommentTimeDec 18th 2011
     
    Loft hatch. Mine was originally a quick fix but it's been in place now for several years. First I sealed the hatch really well using 1 inch wide foam with nice compliance, all glued on with Evo stick.

    Then I just made a big "cuboid" shape of glass wool about a foot thick, all taped up with polythene film. It's a jam fit in the hole. I shove this up, and ease it into place with the loft door stick (it stays put on it's own), then close the (un-insulated) door over it.

    Not ideal, but if you are short of time maybe for you.

    Justin
    • CommentAuthorSeret
    • CommentTimeJan 17th 2012
     
    I have a pretty limited thickness I can apply to mine due to the loft ladder. I just used offcut slabs of rockwool and some of the plastic wrapper they came in, stapled down around the edges. Draft strips around the edges. Quick and dirty, but a whole lot better than the flimsy drafty situation before. U-value is probably only about 0.6, but since it's only 0.5m^2 I think I can live with 0.3W/K.
  27.  
    My timber frame company is supplying one of those fancy air tight insulated attic doors with my frame, AFAIK it's an Austrian made door with ladder. Without having seen it yet, what I have in mind is to create a tunnel above it with one step formed in it to hold back the 700mm of blown mineral wool in the attic. I then plan to make up a block of PIR slightly undersized for the tunnel and stick on a layer of mineral wool to the sides so that it will fit in snugly without any gaps. Probably wrapping the whole thing in tape or foil to avoid loose fibres. The block can then be pushed up into the attic. I'm only going to floor an area of about 20m2 to use for things like Christmas decorations, suitcases and other assorted junk so it probably won't be used more than a handful of times a year.
    •  
      CommentAuthorjoe90
    • CommentTimeJan 18th 2012 edited
     
    Posted By: JSHarrisInteresting to see that there was an ad for just such a beast as this in the flyer that dropped out of the issue of Green Building magazine that popped through my door today. Looks to be a neat job to me, more details here:http://www.ecologicalbuildingsystems.com/workspace/downloads/Dolle-Profi-Plus-Attic-Hatch.pdf" rel="nofollow" >http://www.ecologicalbuildingsystems.com/workspace/downloads/Dolle-Profi-Plus-Attic-Hatch.pdf


    I have fitted loads of these for customers and they are great, but as you say the U value is not very good. If you added the idea from Chris P Bacon above I think you would have a very good solution with a better than most U value.
    • CommentAuthordhutch
    • CommentTimeJan 18th 2012
     
    The area is clearly still in need of a good design.

    In my parents they have just got a loose board, insludated on the back and use a step ladder kept in the storeroom/airingcupboard. However I do not have storage for the ladder and hence want to retain the loft ladder and have a hatch I can remove from ground level (or atlease on no more than a small stool or chair) which does lead to issues.

    So you need.
    - Good airtightness
    - Good insluation
    - Non restrictive to loft ladder
    - Non restrictive to access size
    - Attractive under side

    Its a tall order i dont have the answer to yet.

    Daniel
    •  
      CommentAuthorjoe90
    • CommentTimeJan 18th 2012
     
    I think we have a good solution in the link above from JSH, it has 70mm of insulation and if extra insulation is needed see Chris P Bacon's post above (which I think is brilliant). It has an air seal, it has a loft ladder included (that does not need loads of room in the loft like so many), It is a little larger than the norn but worth the work to be able to get into the loft without doing yoga, the finish is attractive and simple.

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