South Oxfordshire long single garage conversion

Hi all This is a follow-up post that will cover my construction phase, after I initially posted my design and some questions in the "Studio Design" section and received great help in with sme quesiotns and issues I had. The post can be seen here: http://johnlsayers.com/phpBB2/search.php?search_id=egosearch A short summary: The room is made of concrete blockwork, with a loft area upstairs. Below are some renders of what I intend to do. The old garage door will remain (conservation area!! :roll: ), but will be blocked up on the inside using concrete blocks. Notice the ventilation via a fan in the loft area, and 2 silencers for the external leaf in the loft, and two silencers for the inner leaf being put partly inside the internal stud wall (which will be 4x2 studs at 600mm centres), obviously not touching the outer leaf. The inner leaf will be a layer of 18mm OSB3 and a layer of 15mm plasterboard, with Green Glue in between. The reason the grilles for the silencers are at mid-height is because I dont want to lose any more space - so both the internal silencers are connected with the external leaf silencers via insulated flexiduct running between joists in the ceiling cavity. I would welcome any comments or pointers if I have made any serious mistakes, since I am yet to start on the internal leaf or HVAC. The necessary work on the external leaf has already begun. I have ripped out the old loft floor (nasty chipboard) and old joists (hopelessly under-specced and warped), and after consulting a structural engineer, replaced these with new C24 6x2 joists and two layers of 18mm OSB3 - taking care to seal all the joints and gaps with acoustic sealant. The old garage used to have an internal loft ladder through a hole in the loft-floor into the loft, however I have changed access to the loft via a new entrance via a hatch in the gable wall. I have also blocked up one of the windows with concrete blocks, and tried to seal any cracks and holes in the outer leaf with either cement or sealant. Lastly, I have given the inside a few layers of masonry paint. Some photos below. If there are any comments or mistakes so far, please let me know. My next phase is to take out the remaining window, put in a new frame and temporarily glaze it with a clear acryclic sheet. I am gathering quotes for a 21mm piece of laminated glass to go into this new frame - although it does not nearly match the density of the 100mm concrete blockwork, it is about as thick as I want to go and can afford. I will also apply a resin based damp proof membrane (DPM) to the cement floor. When this is done, I will post more photos. I would really appreciate any comments or suggestions from the forum, and will keep posting my progress as I go along in case some of the bits I end up doing can be of help to others Francois

Hi Francois, and Welcome back! :)

Below are some renders of what I intend to do.

I'm curious about the "kinks" in your inner-leaf wall, to get around the "pillars" in the walls: There's nothing wrong with that, if you want do it, but it's a lot of extra work to build. Would it not be easier to just have flat walls, a bit further in? Would you lose a lot of volume/floor area like that?

I am gathering quotes for a 21mm piece of laminated glass to go into this new frame - although it does not nearly match the density of the 100mm concrete blockwork, it is about as thick as I want to go and can afford.

That's fine, and perhaps even a bit overkill. When you do install it in the new frame, try to keep the glass as far "out" as possible (in other words, as far towards the outside world as you can get it: not in the middle of the wall). That's to keep your air gap as large as possible.

I would really appreciate any comments or suggestions from the forum,

It would help if you could post the actual complete final design for your place: that way, we can maybe spot potential issues before you actually build them... :) - Stuart -

Thanks Stuart!

I'm curious about the "kinks" in your inner-leaf wall, to get around the "pillars" in the walls: There's nothing wrong with that, if you want do it, but it's a lot of extra work to build. Would it not be easier to just have flat walls, a bit further in? Would you lose a lot of volume/floor area like that?

The room is not very big - I will lose between 15cm and 20cm of width from the current width of 3.16m. Although it is not major, I am keen to maximise space.

I am gathering quotes for a 21mm piece of laminated glass to go into this new frame - although it does not nearly match the density of the 100mm concrete blockwork, it is about as thick as I want to go and can afford.

That's fine, and perhaps even a bit overkill. When you do install it in the new frame, try to keep the glass as far "out" as possible (in other words, as far towards the outside world as you can get it: not in the middle of the wall). That's to keep your air gap as large as possible.

Thanks - what thickness of laminate glass do you suggest - keen not to unnecessarily overspec / overspend?

It would help if you could post the actual complete final design for your place: that way, we can maybe spot potential issues before you actually build them... :)

Below a top-down view of the plan - hopefully this gives a bit more detail. The inner leaf ceiling will be the same as the walls, hanging from 2x5 c24 joists at 450mm centres. This coming week the external window frame and temporary glazing is going in, along with the DPM. Then the real fun on the internal leaf can hopefully begin. As always, thanks for any help and pointers Francois

... continuing the update on my build. The old window has been removed, and the new sill installed. I have also built the new frame, using mortise and tenon joints (took me ages, don't have the right tools, but I got there in the end), and it is all clamped down, exactly rectangular and will (hopefully!!) stay that way. Next step is to install the frame in the window, and install the window stops. I intend on using 25x25mm stops on both sides of the window, and intend to follow the instructions in the reference area of this blog, titled "hold my hand for my window installed please", found here: http://www.johnlsayers.com/phpBB2/viewtopic.php?t=8400 I have a quote for 21.5mm laminated glass (gulp :shock: its expensive!), and may reduce this to something closer to 16mm to save some money. Stuart, will this be ok, given my internal leaf window will be 12.8mm laminated glass? After installing the window and sealing the perimeter of the frame and the sill my next steps are to install the resin based DPM and install the external leaf door frame. Francois