Comprehensive New Roof plan

shianto

Hi All,

I am looking to undertake full reroofing job on a 158sqm pitched roof. Sorry for the big post, but I thought I would put up the list of works required that should help anyone looking to undertake a similar job (at least as a starting point) based on my own research and reading boards.ie.

Beneath that list are my questions. FYI this is a roof replacement and insulation job only - have decided against installation any renewables as we have flat roof to do that on. Likewise will not prep for HVAC as we might not get the house air-tight enough..

'Known' works

1. Replacement of existing slate (Spanish)
2. Replace of a small Velux Window in roof (new triple glazed)
3. Installation of Insulation (see question below for details)
4. Replacement of Soffit and Fascia with wood (in keeping with the house - know it will close to maintain but OK with that)
5. Replacement of copper flashing with lead
6. Replacement of guttering and downpipes with PVC
7. Removal of rear chimney
8. Repair and repointing of brickwork number of bricks near the top of one of the gables (the wall has shifted)


Contingency allowed for:

1. Repair /replace wallplates
2. Repair/reinforce timber rafters (old style 4.5 inch)
3. Repointing of Front chimney
4. Brickwork near gable


My questions:


1. Slate: Any recommendations in which particular Spanish Slate has the best cost/quality trade-off?
2. Slate: Had a conversation with a person who deals with roof maintenance who advised he is seeing a lot of 5 - 10 year old cement fibre roofs where the slate is starting to curl and that only the more expensive cement fibre should be considered, but as these were comparable to Spainish in price probably just stick with Spanish. Any thoughts welcome.
3. Front Chimney: How should we fill our front chimney as we hoping to give the house good air-tightness (and a HVAC if it makes sense) so won't be using the fireplaces. Any recommendations here?
4. Rear Chimney: It is not possible to see this from the road and as we won't be using thinking of knocking it down - do we need planning permission?
5. Guttering: existing guttering is right against the wall, should it be rehung rehung like that / what is best practice?
6. Insulation: Looking to go for an over/inbetween rafter approach. Have only looked at traditional kingspan i.e. plastboard+full fill (110mm?) inbetween+ 150mm over rafters + Nilvent (or similar)+battens+slate. Can anyone point me to approaches they think are a better cost/quality trade-off?
7. Labour/Coordination: going to employ and contractor/roofing specialist with insurance etc, but want to get spec right first: anything I have missed from the above?

Thanks in advance for any contributions, happy to share my experiences as it goes ahead (hopefully start before Xmas?!)

shianto

Too much info? Feel free to give feedback on the post even...

BryanF

No mention of vapour barrier? (Air-tightness)

Kingspan is a balls to when trying to achieve insulation continuity around confined spaces

Metric Tensor

Had a post written he first day you posted that I then deleted because I reckoned you had done enough research to know most of what I was saying.

1. I'd go for natural slate if you can afford it. Looks wise it is miles better than anything artificial. I have heard of curling of artificial ones but I don't know if it still happens with those manufactured in 2017. Equally I have seen some Spanish natural slates develop rust spots although these do not appear to have affected performance.

2. I'm not too fond on PVC gutters and downpipes myself. Would you consider seamless aluminium for the gutters. A pricier cast aluminium can look well on a particular type/look of house.

Metric Tensor

P.S. If you are not using the attic for anything except storage I'd consider a quilt insulation on the flat.

shianto

BryanF wrote: »

No mention of vapour barrier? (Air-tightness)

Kingspan is a balls to when trying to achieve insulation continuity around confined spaces

RE: air-tightness, yes sorry it is missing but fully intend to have it installed. One of the issues I have however is the roof it hipped (I think that is the term) i.e. part of the first floor walls is in fact the roof, so I am not sure where the air-tightness barrier should be run as I believe it is put typically between the rafters before the insulation - I am getting someone else to do this, but I want to be able to quality check.

On a related point I am hoping that we can get the air-tightness of the house high enough to justify HVAC. That said, I don't know if I should install the air-in / out for a HVAC now and assume we can do a good job, or is that just stupid and I should just punch holes later?

RE: Kingspan (or Xtratherm etc) I have looked at one alternative which was (from memory) wood fibre boards. I am open to anything (although I do consider the cost/benefit). Any alternative recommendations?

shianto

Metric Tensor wrote: »

Had a post written he first day you posted that I then deleted because I reckoned you had done enough research to know most of what I was saying.

1. I'd go for natural slate if you can afford it. Looks wise it is miles better than anything artificial. I have heard of curling of artificial ones but I don't know if it still happens with those manufactured in 2017. Equally I have seen some Spanish natural slates develop rust spots although these do not appear to have affected performance.

2. I'm not too fond on PVC gutters and downpipes myself. Would you consider seamless aluminium for the gutters. A pricier cast aluminium can look well on a particular type/look of house.

Thanks for taking the time to reply at all! Some of your previous posts have indeed shaped my thinking, so if you wanted a rest I wouldn't blame you!

1. I guess you have seen this site www.traditionalroofing.com? Just great. It makes mention of Pyrite being a problem in Spanish Black. Where the ones you saw black?

2. Unfortunately cost is a factor . Percent-wise any ideas of the difference in cost?

Metric Tensor wrote: »

P.S. If you are not using the attic for anything except storage I'd consider a quilt insulation on the flat.

I think the hipped roof might be problematic for ceiling only insulation (I guess that is what you mean by quilt?). Also I am hoping for higher airtightness so I am guess but I think that might. Did I get what you were suggesting?

shianto

BryanF wrote: »

No mention of vapour barrier? (Air-tightness)

Kingspan is a balls to when trying to achieve insulation continuity around confined spaces

Hi Bryan, I just reread my spec and I have specified Nilvent - the Kingspan product. Does this not do the job of air-tightness? I must confess it is the area I am a little confused by (do I need both a breathable membrane and a air-tight membrane, can some be used a both etc). My reading was that was all you need https://www.kingspan.com/gb/en-gb/products/insulation/downloads/product-literature/nilvent

Also under what conditions would you use sarking? really strong constant wind? No where in Dublin I guess(?).

Thanks again!

BryanF

shianto wrote: »

Hi Bryan, I just reread my spec and I have specified Nilvent - the Kingspan product.
1.
Does this not do the job of air-tightness? I must confess it is the area I am a little confused by (
2.
do I need both a breathable membrane and a air-tight membrane, can some be used a both etc).
3.
My reading was that was all you need https://www.kingspan.com/gb/en-gb/products/insulation/downloads/product-literature/nilvent

4.
Also under what conditions would you use sarking?
5. really strong constant wind? No where in Dublin I guess(?).

Thanks again!

1. No
2. Yes (air-tightness layer is often the same thing as a vapour barrier)
3. No
4. Sarking felt is the old version of breathable membrane
5. Nothing to do with air-tightness.

shianto

BryanF wrote: »

1. No
2. Yes (air-tightness layer is often the same thing as a vapour barrier)
3. No
4. Sarking felt is the old version of breathable membrane
5. Nothing to do with air-tightness.

1. Thanks
2. Thanks
3. Thanks
4 & 5 sorry I meant sarking board, not to do with air-tightness just if they used in Ireland - I am probably just being too thorough at this point so feel free to ignore this question...

Metric Tensor

shianto wrote: »

It makes mention of Pyrite being a problem in Spanish Black. Where the ones you saw black?

I honestly can't remember the particular type of slate. I think they may have been Capco branded though and I'm fairly sure they were Spanish.

shianto wrote: »

2. Unfortunately cost is a factor . Percent-wise any ideas of the difference in cost?

Not a clue. Sorry!

shianto wrote: »

I think the hipped roof might be problematic for ceiling only insulation (I guess that is what you mean by quilt?). Also I am hoping for higher airtightness so I am guess but I think that might. Did I get what you were suggesting?

There's no reason for the hipped roof to cause a problem for insulation on the ceiling. The insulation will have to be treated along the hip end the same as it would on the non hipped end. (i.e. use proprietary cards to allow ventilation along the underside of the felt.) I'm not sure what you are saying about the air-tightness layer .... that would usually be below the insulation in the ceiling unless you have some sort of converted attic.