Green Building Forum - converting pub Sat, 27 Jun 2026 06:33:40 +0100 https://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 converting pub https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=178561#Comment_178561 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=178561#Comment_178561 Mon, 24 Jun 2013 21:51:25 +0100 bogal2
The pub floor area is 190m2 on the ground floor and has a very damp west gable wall due to higher ground levels outside. I intend to deal with this by tanking the inside wall after installing some drainage ouside which is limited by the foundations being only 50ch deep!

I have planning permission to externally insulate and remove the bay windows, which have leaky recessed roofs.

My plan, at present, is:

Insulate the walls with 120mm of PIR and render after leveling the present render. Is this ok with a still damp wall on the west side despite having removed internal render up to 1m on the inside several months ago?

Insulate the floor with 100mm PIR floating floor which will require a few door frames to be raised. About 50% of the floor has a suspended floor over a cellar. The rest has an old concrete floor with bitumen over. The cellar entrance will presumably need insulating too.

To cover EWI I intend to extend the roof and insulate between the joists with warmcell on top of an intelligent membrane to create a cold roof. This seems to leave a diificult to avoid thermal bridge at the eaves, any suggestions how to avoid this? A warm roof seems to be a bit of a waste of an unused heated area?

I intend to install MVHR and will need some sound insulation to mask the barking!

Any comments on this strategy and whether or not it will result in a significant reduction in energy use would be appreciated!]]> converting pub https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=178568#Comment_178568 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=178568#Comment_178568 Mon, 24 Jun 2013 22:20:03 +0100 jamesingram Re. eaves and over wall plate , use PUR or phen. between rafters to meet warmcell . rather than vice-a-versa.
you still get thermal bridge from rafters but inbetween performs better.
Vent cold roof above foam board insulation with 10mm vent on top of fascia and air gap above board or
tile vents positioned a row above .
cheers]]> converting pub https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=178569#Comment_178569 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=178569#Comment_178569 Mon, 24 Jun 2013 22:50:22 +0100 Nick Parsons
If you get the insulation and air-tightness right you will undoubtedly see a massive improvement in comfort and reduction in running costs, but you won't be right down near EnerPHit levels. Likely U value for walls c 0.17 with 120mm PIR @ lambda of 0.022.]]> converting pub https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=178780#Comment_178780 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=178780#Comment_178780 Thu, 27 Jun 2013 19:38:09 +0100 jamesingram converting pub https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=178829#Comment_178829 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=178829#Comment_178829 Fri, 28 Jun 2013 09:43:59 +0100 davidfreeborough
David]]> converting pub https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=179051#Comment_179051 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=179051#Comment_179051 Tue, 02 Jul 2013 00:32:13 +0100 bogal2
I suppose I could move my parents in!]]> converting pub https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=179060#Comment_179060 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=179060#Comment_179060 Tue, 02 Jul 2013 09:03:44 +0100 davidfreeborough
You also need to consider how to seal the wind/air barriers & join up the roof/wall insulation in a way that avoids thermal bypass/bridging. It looked in the picture like there may be some sloping ceilings. How do you plan to join these with the main roof? Especially when adding EWI, it may be easier to get the wind/air barriers & insulation to line up by using a warm roof.

How is the loft used at the moment? Can you afford to cover it in insulation? How practical will it be to seal the flat ceiling? Are there lots of services breaking through into the loft? What about when you add the services required for the flats? If you can covert this space into a master bedroom for a loft apartment or move storage space from elsewhere then it may allow you to make better use of the other spaces.

David]]> converting pub https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=179066#Comment_179066 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=179066#Comment_179066 Tue, 02 Jul 2013 10:48:41 +0100 Ed Davies Posted By: davidfreeboroughthe heated envelope will increase by ((2 x Cos(roof_pitch))-1)x100%I don't see how that can be right. If the roof_pitch was zero (flat roof, cos = 1) then that'd be a 100% increase, if the pitch was 60° (cos = 0.5) then a 0% increase and for 80° (yes silly, but cos = 0.1736) a 65% decrease.

I think it's ((1 / cos(roof_pitch)) - 1) × 100%.

>>> inc = lambda pitch: ((1/math.cos(math.radians(pitch))) - 1) * 100
>>> inc(0)
0.0
>>> inc(60)
99.99999999999996 [[ i.e., 100% give or take real arithmetic rounding effects ]]
>>> inc(80)
475.8770483143631
>>> inc(45)
41.421356237309496
>>> inc(30)
15.470053837925146

I.e., 60° slope doubles the area whereas a 30° slope increases by just over 15%.

Plus the extra exposed gable end.]]> converting pub https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=179079#Comment_179079 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=179079#Comment_179079 Tue, 02 Jul 2013 14:56:38 +0100 davidfreeborough
Yes, you're right, my fingers were working faster than my brain.

David]]> converting pub https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=179634#Comment_179634 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=179634#Comment_179634 Wed, 10 Jul 2013 13:18:36 +0100 bogal2 converting pub https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=180736#Comment_180736 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=180736#Comment_180736 Sat, 27 Jul 2013 15:25:43 +0100 fostertom
First, I strongly agree with
Posted By: davidfreeboroughput the insulation on top of the existing rafters & make it a true warm roof
Think unbroken tea-cosy of insulation and airtightness - removes so many tricky problems and fail-points (despite best efforts) at a stroke, ensures best poss true performance out of the materials chosen.

The render, if cracks are well pointed or maybe mastic'd, wd be your airtight layer, and sheathing over the rafters wd be same on the roof - just need to join the two robustly.

While you're at it, why settle for only 120mm of expensive PIR as EWI - why not 200 or more of much cheaper EPS, either dirt-cheap white @ .038, or better VFM grey @ .031? EPS is significantly more vapour permeable than foam plastics, and far more eco-virtuous.

Don't worry about levelling the render - the cementitious adhesive allows much adjustment and anyway can follow the curve. Key thing is condition of the paint finish - if really sound you can fix the EWI simply with the adhesive, but if any doubt at all you'll need all the bother of mechanical fixings. Get the EWI materials rep in at an early stage - in the SW, the Parex rep is really excellent.

Is it a plasticy, vapour impervious paint, or if you're lucky a mineral 'breatheable' paint (check all layers). If impervious, that's a drag, because it'll seriously prolong the wall drying-out process to years - can only dry inward - so likewise make sure internal finishes (all layers, existing and new) are 'breatheable' and remain so in future. Ability to dry inward (as well as outward) will also help the health of the outer EPS too, which can (and does) absorb huge amounts of water as vapour, thro the acrylic render, quite safely, provided it can dry out.

Might be worth scabbling off as much as poss of the paint, where loose. It should be the render, not the paint, that will provide the airtightness.

What's the plan about windows?]]> converting pub https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=180737#Comment_180737 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=180737#Comment_180737 Sat, 27 Jul 2013 16:04:14 +0100 Nick Parsons converting pub https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=180738#Comment_180738 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=180738#Comment_180738 Sat, 27 Jul 2013 16:38:20 +0100 fostertom
Anyway I bet the main damp source is failed render sucking in the rain thro capillary cracks - so is excellent to stop that constant addition, by EWI, must be breatheable, and start the drying out, which may take years. Doubt it's the render or plaster that are preventing drying out - maybe vapour impermeable paint on either or both tho.

If damp is really due instead, or as well, to raised ground, then that shd be tackled at source, with french drain, in fact I'd run a french drain right round the perimeter, as deep as poss to bott of found, and run the EWI right down, either EPS and/or Leca, as frequently discussed here - can simplify matters by removing need for u/floor insulation.

Internal tanking is a desperate and unreliable last measure - e.g. if too close to boundary for a french drain - which can only be a condensation sink esp in an otherwise well insulated building.

And let no one mention 'rising damp' - it's hardly ever that.]]> converting pub https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=180739#Comment_180739 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=180739#Comment_180739 Sat, 27 Jul 2013 16:59:04 +0100 Nick Parsons
Sure it is. Ext GL is raised compared to int floor level, and footings ridiculously shallow. Render is extremely hard sand/cement, so I expect it *is* helping tp prevent drying-out. I have suggested lime plaster internally to allow the long drying-out process to occur, and definitely not tanking.

''in fact I'd run a french drain right round the perimeter, as deep as poss to bott of found,''

Think footing on W side at least is less than 500 below ext GL! If I recommended a french drain it would be a long way from the wall!]]> converting pub https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=180742#Comment_180742 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=180742#Comment_180742 Sat, 27 Jul 2013 17:19:13 +0100 fostertom
The OP said tanking- we agree not gd.

Even hard cem render, concrete etc is good and vapour permeable - what it resists is liquid, so if it lets liquid in thro cracks it can't get out again as liquid, but it can, readily, as as vapour - however liquid is being added faster than it can dry by vapourisation. It seems that lime render's advantage is not so much that it's particularly vapour permeable, but that it hairlines all over so doesn't develop the fewer but wider v efficient liquid-pumping capillary cracks that hard cem render does.

Gypsum render internally is also good and vapour permeable - but won't like the brick it's applied to taking months to begin to dry. Not sure about 'renovating plaster' which can tolerate that - may have low vapour permeability. But will even lime render 'set' properly under those circs?

The french drain can be ever so shallow, as long as its drained bottom is below FL - in which case the perimeter insulation becomes a bed of Leca as thick as you like, even rising above FL, as a broad 'wing' of insulation, as opposed to a thinner downstand 'blade' of EPS.]]> converting pub https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=180744#Comment_180744 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=180744#Comment_180744 Sat, 27 Jul 2013 17:48:34 +0100 Nick Parsons
Don't apologise, FT. I wasn't trying to score points - with my sense of direction I was willing to believe I'd got it the wrong way round!]]> converting pub https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=180746#Comment_180746 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=180746#Comment_180746 Sat, 27 Jul 2013 18:18:10 +0100 Nick Parsons
To be honest, I don't have experience of applying it in damp conditions.Seeing it already on, and working, in damp conditions, yes.

But I do understand that hydraulic lime can achieve a set even underwater - hence its use in canal locks.]]> converting pub https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=180751#Comment_180751 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=180751#Comment_180751 Sat, 27 Jul 2013 19:20:58 +0100 djh Posted By: Nick Parsons''But will even lime render 'set' properly under those circs?''

To be honest, I don't have experience of applying it in damp conditions.Seeing it already on, and working, in damp conditions, yes.

But I do understand that hydraulic lime can achieve a set even underwater - hence its use in canal locks.
AIUI, the presence of water is not a problem. Even air lime will cure in the damp. In fact you have to spray it to keep it damp at first. But it needs CO2 to cure and that is what is not easily available under water and why hydraulic lime is used for canal locks, lighthouses etc. Hydraulic lime will certainly set faster.]]> converting pub https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=180752#Comment_180752 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=180752#Comment_180752 Sat, 27 Jul 2013 19:23:57 +0100 djh Posted By: fostertomEven hard cem render, concrete etc is good and vapour permeable - what it resists is liquid, so if it lets liquid in thro cracks it can't get out again as liquid, but it can, readily, as as vapour - however liquid is being added faster than it can dry by vapourisation. It seems that lime render's advantage is not so much that it's particularly vapour permeable, but that it hairlines all over so doesn't develop the fewer but wider v efficient liquid-pumping capillary cracks that hard cem render does.
I don't believe this is correct, but don't have time at the mo to check the facts. Certainly lime is more vapour permeable, and concrete stays damp.

For internal application, is clay plaster being considered as well as lime? It's more permeable and hygroscopic.]]> converting pub https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=180759#Comment_180759 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=180759#Comment_180759 Sat, 27 Jul 2013 23:49:52 +0100 bogal2 For windows I was thinking of triple glazed fixed in place by on exterior face of present walls linking up with EWI.]]> converting pub https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=180765#Comment_180765 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=180765#Comment_180765 Sun, 28 Jul 2013 08:39:40 +0100 fostertom
Leca, being mineral, is better than EPS as 'wing', with topsoil over. On the drawing, there's geotextile membrane under and up the trench side, to prevent soil fines from clogging it up over time (but the geotextile itself clogs eventually) and there's v tough DPM over the top and up the EPS, as root barrier.

Heat loss from floors is mainly from the perimeter, to surrounding surface, as described, but also straight down. However the deep subsoil straight down doesn't stay stone cold forever - over a year or two it gradually warms up so downward loss tapers off and thereafter its mass helps to keep the floor warm in winter and cool in summer.

This method works both for solid floors and for suspended floors over void space - either way the floor needn't be disturbed - nor waterproofed, because whatever water source there might have been is drained by the french drain. Hopefully. However, be v sure there's no existing rot etc if it's a timber suspended floor.]]> converting pub https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=180774#Comment_180774 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=180774#Comment_180774 Sun, 28 Jul 2013 09:27:11 +0100 Triassic Posted By: fostertomEven hard cem render, concrete etc is good and vapour permeable - what it resists is liquid, so if it lets liquid in thro cracks it can't get out again as liquid, but it can, readily, as as vapour - however liquid is being added faster than it can dry by vapourisation. It seems that lime render's advantage is not so much that it's particularly vapour permeable, but that it hairlines all over so doesn't develop the fewer but wider v efficient liquid-pumping capillary cracks that hard cem render does.we have a 14inch solid wall extension which was cement rendered outside and modern plaster inside. The plaster had damp patches all over it, particularly where there were cracks in the external render. We hacked the render and plaster off and 're-rendered and plastered in lime and the damp was cured. Oh and we used a breathable clay based pain inside.]]> converting pub https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=180777#Comment_180777 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=180777#Comment_180777 Sun, 28 Jul 2013 10:20:41 +0100 fostertom converting pub https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=180778#Comment_180778 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=180778#Comment_180778 Sun, 28 Jul 2013 12:31:27 +0100 bogal2
I understand that foundations rely on support below extending down into the earth at a 45 degree angle so how near, horizontally and vertically to this slightly concerning foundation should I go?

The west gable wall has cellars at the perimeter on the outer two thirds so maybe the inner third of the foundations don't have much structural importance? I wish I had met a structural engineer or architect with your sense! They don't seem to exist in Wigan surprisingly!

East wall has a different problem. It has a shared boundary with neighbours access to his steel fabricating workshop for lorries- never seen one going up there though! He says I can put up to 5 cm external insulation on that wall but doesn't want more. Would 5cm Pir EWI and some Iwi work? Or should I just offer him a cash incentive to let me put a bit more EWI on!]]> converting pub https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=180779#Comment_180779 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=180779#Comment_180779 Sun, 28 Jul 2013 13:18:38 +0100 fostertom
Be very sure the trench bottom doesn't get rained on or fill with ground water - be ready to drain any such out immediately - and above all, if wet, don't walk on it and turn the virgin clay to slurry. If that happens, quickly dig out the softened stuff and replace with weak concrete, before squish starts to happen.

If 50cm deep, how about a 300dp bed of Leca extending outward say 1m, topsoiled over. Run the EPS down the wall to just bury itself into the Leca. Where the basement wall drops deeper, you have the option to make it all vertical, deeper.

If in any doubt, get practical on the spot advice - don't take what I say as any more than a suggestion of possibility!]]> converting pub https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=180780#Comment_180780 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=180780#Comment_180780 Sun, 28 Jul 2013 13:25:43 +0100 fostertom converting pub https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=180781#Comment_180781 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10824&Focus=180781#Comment_180781 Sun, 28 Jul 2013 14:10:11 +0100 Nick Parsons