Semi D Renovation - Insulation, Air Tightness and Ventilation

Ush1

I have a typical 3 bed semi with an attic conversion and am currently looking into getting a large amount of renovation work done but want to make sure my insulation, air tightness and ventilation strategy is the best it can be.

The converted attic has already been renovated and is insulated with 50mm foil back boards between the rafters, then another layer of 50mm insulated slabs running below them. This insulation layer runs right to the soffits (warm storage in eaves).

3 of the below bedrooms are also renovated with 50mm insulated slabs. The bathroom is not done and none of the ground floor of the house.

The house has a redbrick front with a cavity(no insulation) and inner leaf, the other three sides are cavity blocks. My questions are as follows:

1. Should I look at getting external insulation for all walls? Would this be an issue with the redbrick front and if so would external insulation on the other three walls and either drylining the front or pumping the cavity work best?

2.Because of the mount of internal renovation work(new bathroom, stairs, kitchen, removal of front porch, etc..) would it make more sense money wise to dryline internally as this work is done?

3.There is no airtightness membrane. Hard to find stuff online detailing how this works with insulated slabs. Would this be needed and is it worth it baring in mind I don't want to have to rip out the slabs in the already renovated rooms upstairs? Should I partially air tighten the areas being renovated?

4.In the renovated rooms there are no vents currently and am reluctant to slap a hole in the wall for passive ventilation. What's the best recommendation here? MHVR seems to be only worth it if airtightness is at a high level. Would a DCV solution be best?

Thanks.

Calahonda52

are there vents in the window in the already reno'd rooms?
is this now a three storey house?

Ush1

Calahonda52 wrote: »

are there vents in the window in the already reno'd rooms?
is this now a three storey house?

No, for the moment the windows are left slightly open in the reno'd rooms.

Technically three storey yes with the attic conversion. In the attic there is vents open in the two velux windows also.

Calahonda52

Ush1 wrote: »

No, for the moment the windows are left slightly open in the reno'd rooms.

Technically three storey yes with the attic conversion. In the attic there is vents open in the two velux windows also.

So no ventilation in the bedrooms?
Are you happy with that and that it meets the regs?

Did the conversion meet the fire requirements: am presuming it is used as a bedroom/etc and not storage.
Is there a fixed stairs to attic?
http://www.housing.gov.ie/search/archived/current/category/housing/type/publications?query=loft%20conversion

Ush1

Calahonda52 wrote: »

So no ventilation in the bedrooms?
Are you happy with that and that it meets the regs?

No hence I'm asking the best strategy for ventilation.

Calahonda52 wrote: »

Did the conversion meet the fire requirements: am presuming it is used as a bedroom/etc and not storage.
Is there a fixed stairs to attic?
http://www.housing.gov.ie/search/archived/current/category/housing/type/publications?query=loft%20conversion

There is a fixed stairs but not used as a bedroom.

Calahonda52

OKAY, Thanks for this, I will leave it to the experts here now..

My instinct is that DCV is more suitable because, IIRC, there are additional issues with MVHR in a 3 storey: fire dampers etc

Is ground floor suspended timber or concrete?

If you go with EWI, it should go up through soffits to meet, in an airtight way, the rafter insulation: think wooly hat in winter.
The cavity wall would then be pumped with beads, the cavity block is more problematic

Ush1

Calahonda52 wrote: »

OKAY, Thanks for this, I will leave it to the experts here now..

My instinct is that DCV is more suitable because, IIRC, there are additional issues with MVHR in a 3 storey: fire dampers etc

Is ground floor suspended timber or concrete?

If you go with EWI, it should go up through soffits to meet, in an airtight way, the rafter insulation: think wooly hat in winter.
The cavity wall would then be pumped with beads, the cavity block is more problematic

I think the lack of airtightness will also render MVHR useless but open to correction.

Ground floor is concrete which actually reminds me of another question. The floor is going to be replaced but just wondering is there any way to place insulation under the floor? I notice a lot of cold comes off the floor.

Could another problem with EWI be that some of the walls are also drylined? EWI would be used on cavity block walls, can't be pumped.

Gumbo

Calahonda52 wrote: »

My instinct is that DCV is more suitable because, IIRC, there are additional issues with MVHR in a 3 storey: fire dampers etc

+1
Dampers or similar fire proofing required around all ducts in 3 strorey houses.
Example would be the Tenmat Firefly Ceiling Air Valve.

OP, how deep are you going with this retrofit?
You would want to go back to bare block walls.
Decide on your method, whether that be EWI, Internal etc and get somebody experienced in retrofits to do the calculations.

Ush1 wrote: »

Ground floor is concrete which actually reminds me of another question. The floor is going to be replaced but just wondering is there any way to place insulation under the floor? I notice a lot of cold comes off the floor.

Why is the ground floor being replaced? Pyrite Remediation?

Ush1

kceire wrote: »

+1
Dampers or similar fire proofing required around all ducts in 3 strorey houses.
Example would be the Tenmat Firefly Ceiling Air Valve.

OP, how deep are you going with this retrofit?
You would want to go back to bare block walls.
Decide on your method, whether that be EWI, Internal etc and get somebody experienced in retrofits to do the calculations.

Going back to the bare block everywhere apart from the already renovated bedrooms and attic.

I'm not sure which method really, hoping someone can advise based on the information.

kceire wrote: »

Why is the ground floor being replaced? Pyrite Remediation?

Sorry I mean the flooring, basically removing tiles and floor boards but if there is a way I can insulate under the floor I'd be interested.

Gumbo

Ush1 wrote: »

Going back to the bare block everywhere apart from the already renovated bedrooms and attic.

That's good, you can really make a good dent in it then. The walls would want to be sand/cement rendered internally but the attic is the one place you need to put in air tight measures.

Ush1 wrote: »

I'm not sure which method really, hoping someone can advise based on the information.

This is where you engage a professional with experience with deep retrofits of existing dwellings.

SR54 Code of Practice

Ush1 wrote: »

Sorry I mean the flooring, basically removing tiles and floor boards but if there is a way I can insulate under the floor I'd be interested.

Agh right, no real way of insulating then.

Calahonda52

SR 54
https://www.nsai.ie/about/news/publication-of-sr-542014-code-of-practice

Well one way of getting the show on the road is to get a blower door test done when you have it all ripped out and see what the number is.
You could also look at getting a test done on the individual reno-ed bedrooms.
If they have no wall/window vents then it should be easy enough
Talk to the tester before hand.

Pictures are very useful also.
Any down lighters?

Lumen

kceire wrote: »

Agh right, no real way of insulating then.

From what I've read, whilst the PIR products are designed to go under a screed, there are other products designed to be used under wooden floors.

For instance, 40mm woodfibre with a screw strip.

Or does that still create too many problems with thresholds and step heights to be acceptable?

edit: manufacturer name in photo, oops

Ush1

Since all the floors will be coming up, could the concrete underneath be kangoed up to a certain depth, insulation then placed down and some sort of cement on top?

Gumbo

Lumen wrote: »

From what I've read, whilst the PIR products are designed to go under a screed, there are other products designed to be used under wooden floors.

For instance, 40mm woodfibre with a screw strip.

Or does that still create too many problems with thresholds and step heights to be acceptable?

edit: manufacturer name in photo, oops

The problem is that you now have reduced the floor to ceiling heights by at least 40mm. Front door entry, internal doors, skirting and everything else now has to be made to suit. You may also reduce your habitable space height requirements under Part F.

Gumbo

Ush1 wrote: »

Since all the floors will be coming up, could the concrete underneath be kangoed up to a certain depth, insulation then placed down and some sort of cement on top?

No. You only have a 150mm concrete slab there. You can not reduce the think was of this. You would have to remove the whole slabs down below the compacted hardcore layers in order to make enough space to put insulation in there

Calahonda52

Ush1 wrote: »

Since all the floors will be coming up, could the concrete underneath be kangoed up to a certain depth, insulation then placed down and some sort of cement on top?

Best to refer to the floor covering coming up, at least for now:D

The payback on redoing the floor can be CRUDELY estimated as follows

http://www.concrete.org.uk/fingertips-document.asp?id=593

assume a k value of 2 (W/m.K) for an uninsulated slab on ground and a slab thickness of 0.15 meters, then the R value could be .15/2 = 0.075 (m2K/W)

U value is 1/0.075 = 13(W/m2.K)

It should be 0.45 for an older house and .21 for new [(W/m2.K) ]

so assume a floor slab of 100 sq meters, a delta T of 10 gives a heat loss of 13 kWh for no insulation
as opposed to 0.21 kWh for an insulated slab to Part L

{ this may be wrong in the detail, the approach is right, maybe one of the others will crunch it more accurately.}

[U Values
The conduction of heat is quantified using the thermal conductivity coefficient, or k-value (W/m.K), of the materials used in its construction. This is the rate at which heat flows through a material between points at different temperatures. The thermal resistance, or R-value (m2K/W), is calculated by dividing the thickness of the material (in metres) by the k-value. From this the thermal transmittance, U-value (W/m2.K) of a building element, is calculated as the inverse of the sum of the R-values of the component parts and adjacent air layers.

The U-value is the measure of heat transmittance through a material and the lower the U value the less heat is transmitted through a construction i.e. the better the insulation quality.]

Ush1

Thanks for that but it sounds like I can't easily reduce the thickness of the floor slab?

I also need to blank off a fireplace in the sitting room, what's the best way of doing this?

Calahonda52

Ush1 wrote: »

..

I also need to blank off a fireplace in the sitting room, what's the best way of doing this?

if a deep refurb, remove it entirely

Ush1

Calahonda52 wrote: »

if a deep refurb, remove it entirely

Would that add significant expense? The chimney goes up through one of the already renovated bedrooms. I presume I cant remove it from the lower floor and leave it above?

Gumbo

Ush1 wrote: »

Would that add significant expense? The chimney goes up through one of the already renovated bedrooms. I presume I cant remove it from the lower floor and leave it above?

No need to remove the structure thus not effecting the finished rooms upstairs.
Block it up adequately to ensure not uncontrolled air loss.

Ush1

kceire wrote: »

No need to remove the structure thus not effecting the finished rooms upstairs.
Block it up adequately to ensure not uncontrolled air loss.

Thanks. I've heard some conflicting ideas on this. Should I leave a vent there or block it completely? Baring in mind that the chimney is shared with my attached neighbour and so the chimney won't be blocked at the top.

Gumbo

Ush1 wrote: »

Thanks. I've heard some conflicting ideas on this. Should I leave a vent there or block it completely? Baring in mind that the chimney is shared with my attached neighbour and so the chimney won't be blocked at the top.

That's where your supervising professional will advise on the specifics.

Calahonda52

Calahonda52 wrote: »

if a deep refurb, remove it entirely

Ignore, missed the semi-d bit