Hello,
I have concrete plans to insulate a cold roof of a house built in the 1950s, as the energy loss and lack of fire protection can no longer be tolerated.
The planned construction and the current condition can be seen in the pictures.
100mm (4 inches) insulation between rafters, 50mm (2 inches) insulation below rafters
The missing under-roof membrane (breather membrane) is intended to be retrofitted next summer. However, ventilation is ensured because the roof has ventilation tiles and a ventilated ridge.
The roof structure and tiles will be thoroughly cleaned from the inside and disinfected with 70% isopropanol to eliminate any spore contamination.
I am asking here to avoid any mistakes. The only point not compliant with EnEV (energy saving regulation) in this plan, as far as I can see, is the insulation below the rafters (50mm), which makes up slightly more than 20% of the total insulation thickness—correct?
I am grateful for any constructive criticism. If there are no issues, I would also appreciate confirmation from your perspective.
I have concrete plans to insulate a cold roof of a house built in the 1950s, as the energy loss and lack of fire protection can no longer be tolerated.
The planned construction and the current condition can be seen in the pictures.
100mm (4 inches) insulation between rafters, 50mm (2 inches) insulation below rafters
The missing under-roof membrane (breather membrane) is intended to be retrofitted next summer. However, ventilation is ensured because the roof has ventilation tiles and a ventilated ridge.
The roof structure and tiles will be thoroughly cleaned from the inside and disinfected with 70% isopropanol to eliminate any spore contamination.
I am asking here to avoid any mistakes. The only point not compliant with EnEV (energy saving regulation) in this plan, as far as I can see, is the insulation below the rafters (50mm), which makes up slightly more than 20% of the total insulation thickness—correct?
I am grateful for any constructive criticism. If there are no issues, I would also appreciate confirmation from your perspective.
A
AallRounder13 Sep 2013 07:21Hello jfhde,
before you dive into energy regulations and the like, I see the problem here:
"The missing underlay membrane should ideally be retrofitted next summer."
How is that supposed to happen? Apparently, you want to keep the existing roof covering in place, if I understand correctly. It seems to be an old mortar roof, with mortar applied to the head and at least partially to the side lap. However, there seem to have been problems because someone used a large foam gun. Was the roof leaking in those areas? Foam sealant doesn’t last forever, and eventually the old issues will return. Neither roof tiles nor roofing mortar are waterproof materials, so quick water drainage through correct and undamaged installation at the recommended roof pitch is crucial. What exactly was the problem?
Attaching an underlay membrane beneath the rafters is always a critical solution, especially when everything is to be nailed down with mineral wool. Is living space going to be created directly under the roof, or do you simply want to prevent heat loss through the roof? In the latter case, proper insulation of the ceiling below the attic would be sufficient.
By the way, how is the ventilation at the eaves? Ventilated tiles and ridge ventilation are fine, but air should also be able to enter from below through the eaves or soffit.
Regards
AallRounder
before you dive into energy regulations and the like, I see the problem here:
"The missing underlay membrane should ideally be retrofitted next summer."
How is that supposed to happen? Apparently, you want to keep the existing roof covering in place, if I understand correctly. It seems to be an old mortar roof, with mortar applied to the head and at least partially to the side lap. However, there seem to have been problems because someone used a large foam gun. Was the roof leaking in those areas? Foam sealant doesn’t last forever, and eventually the old issues will return. Neither roof tiles nor roofing mortar are waterproof materials, so quick water drainage through correct and undamaged installation at the recommended roof pitch is crucial. What exactly was the problem?
Attaching an underlay membrane beneath the rafters is always a critical solution, especially when everything is to be nailed down with mineral wool. Is living space going to be created directly under the roof, or do you simply want to prevent heat loss through the roof? In the latter case, proper insulation of the ceiling below the attic would be sufficient.
By the way, how is the ventilation at the eaves? Ventilated tiles and ridge ventilation are fine, but air should also be able to enter from below through the eaves or soffit.
Regards
AallRounder
Good morning,
thank you for the detailed response. I will take a closer look at how well the ventilation via the eaves or soffit is designed, and if necessary, I will need to add a ventilation path behind the soffit cladding. Thanks for the tip.
Unfortunately, I cannot say exactly why the expanding foam was applied, as this probably happened around the late 1980s—most likely to prevent drafts or to fix the polystyrene, since since then there has been a living space directly next to this room. They are separated only by a stud wall with 15mm (0.6 inch) polystyrene and 12.5mm (0.5 inch) drywall between. The room itself is insulated with the same polystyrene panels between the rafters, also fixed with expanding foam, and covered with plywood panels in front. I don’t even want to estimate how many tens of thousands of kWh have been wasted through this with the storage heater and convection heater venting heat out through the roof. Therefore, proper insulation must be installed as a priority before the next heating season begins.
In summer, I would like to reroof the house with an underlay membrane and, if financially possible, add additional insulation above the rafters—that is what I meant by upgrading.
The proper water drainage was probably compromised with the current setup because only the attic has the polystyrene panels installed. On the first floor, in the roof slopes, there is what I was told is straw mat insulation from the 1950s. So any condensation or penetrating moisture would have been directed toward the straw mats or through leaking panels toward the plywood wall, which likely means a complete renovation of the entire roof structure will be unavoidable in the near future. I hope the rafters are still in good condition everywhere, like they appear to be in the attic.
Long story short—the current insulation should continue to be used later but needs to be installed immediately because the occupied room generates enormous energy costs and is still barely maintainable at room temperature.
In your opinion, is this setup acceptable for that purpose?
Regards,
jfhde
thank you for the detailed response. I will take a closer look at how well the ventilation via the eaves or soffit is designed, and if necessary, I will need to add a ventilation path behind the soffit cladding. Thanks for the tip.
Unfortunately, I cannot say exactly why the expanding foam was applied, as this probably happened around the late 1980s—most likely to prevent drafts or to fix the polystyrene, since since then there has been a living space directly next to this room. They are separated only by a stud wall with 15mm (0.6 inch) polystyrene and 12.5mm (0.5 inch) drywall between. The room itself is insulated with the same polystyrene panels between the rafters, also fixed with expanding foam, and covered with plywood panels in front. I don’t even want to estimate how many tens of thousands of kWh have been wasted through this with the storage heater and convection heater venting heat out through the roof. Therefore, proper insulation must be installed as a priority before the next heating season begins.
In summer, I would like to reroof the house with an underlay membrane and, if financially possible, add additional insulation above the rafters—that is what I meant by upgrading.
The proper water drainage was probably compromised with the current setup because only the attic has the polystyrene panels installed. On the first floor, in the roof slopes, there is what I was told is straw mat insulation from the 1950s. So any condensation or penetrating moisture would have been directed toward the straw mats or through leaking panels toward the plywood wall, which likely means a complete renovation of the entire roof structure will be unavoidable in the near future. I hope the rafters are still in good condition everywhere, like they appear to be in the attic.
Long story short—the current insulation should continue to be used later but needs to be installed immediately because the occupied room generates enormous energy costs and is still barely maintainable at room temperature.
In your opinion, is this setup acceptable for that purpose?
Regards,
jfhde
A
AallRounder13 Sep 2013 08:39Hello jfhde,
"In summer, I would like to reroof with an underlay membrane and, if financially possible, also add additional insulation above the rafters. That’s what I meant by retrofitting."
- Okay, that clears up my concerns about the underlay membrane and roof watertightness. It’s good that the terrible polystyrene construction is being removed. Luckily, it seems the wood wasn’t damaged.
I would definitely not install the insulation before the roof renovation. First, in winter, any leaks could cause moisture or wind-driven snow to damage the mineral wool. And roofing contractors will appreciate it if they don’t have to work around existing insulation when reroofing. Dirt will get in, an old tile might fall, and the entire underlying structure could be damaged. Not to mention if the new underlay membrane isn’t installed quickly enough and rain gets in: that leads to large amounts of contaminated waste, and the expensive insulation has to be removed. It’s better not to use the space upstairs until everything is properly renovated.
For compliance with energy-saving regulations, there are much more knowledgeable experts in this forum than me—for example, €uro.
Regards,
AallRounder
"In summer, I would like to reroof with an underlay membrane and, if financially possible, also add additional insulation above the rafters. That’s what I meant by retrofitting."
- Okay, that clears up my concerns about the underlay membrane and roof watertightness. It’s good that the terrible polystyrene construction is being removed. Luckily, it seems the wood wasn’t damaged.
I would definitely not install the insulation before the roof renovation. First, in winter, any leaks could cause moisture or wind-driven snow to damage the mineral wool. And roofing contractors will appreciate it if they don’t have to work around existing insulation when reroofing. Dirt will get in, an old tile might fall, and the entire underlying structure could be damaged. Not to mention if the new underlay membrane isn’t installed quickly enough and rain gets in: that leads to large amounts of contaminated waste, and the expensive insulation has to be removed. It’s better not to use the space upstairs until everything is properly renovated.
For compliance with energy-saving regulations, there are much more knowledgeable experts in this forum than me—for example, €uro.
Regards,
AallRounder
Allrounder schrieb:
...
I definitely wouldn’t install the insulation before the roof renovation. First of all, in winter, the mineral wool could get damaged by moisture or blowing snow through possible leaks, and during the reroofing, the roofers won’t be happy having to work around existing insulation. Dirt will get in, an old tile might fall, and the entire underlying structure could be damaged. Not to mention, if the new underlayment isn’t installed quickly enough and it rains inside, you’ll end up with cubic meters of hazardous waste and the expensive insulation will have to be removed. It’s better not to use that space until everything is properly renovated.
For compliance with energy-saving regulations, there are much more knowledgeable experts here on the forum than me; I’m thinking, for example, of €uro.
...Hello,
you’re probably right to be concerned. I’ve run through all the scenarios in my head, and none is really ideal because I can’t just move the resident of the upstairs room due to lack of alternative housing. Now it’s probably just a matter of weighing up which less-than-perfect solution to choose for this heating season...
I checked the eaves and soffit today; they were sealed nicely some time ago, but the mortar is more sandy than solid and is barely present in the lower rows, allowing air to flow through the bricks. This definitely needs urgent repair.
While I was at it, I inspected the roof at the upper floor level with an endoscope camera—the rafters appear untouchable, they look like new, even though the styrofoam boards and the roof box covering look dark gray to black, so they seem quite moldy. In the attic, where the rafters are exposed and in the roof space, I haven’t seen any live insects yet. Probably not the typical appearance of an almost 60-year-old roof frame, especially one where the wood has long dried out and was untreated, and then "insulated," or rather mistreated, this way?! Apparently, it’s supposed to be untreated wood, or so I was told. But the vinyl flooring in the bathroom (built around 1980, with a "tar" coating) is supposed to stay and was still okay... Well, spending half the time planning urgently needed renovations and the other half trying to convince the actual homeowner of the necessity is quite an amusing pastime. But I’m probably drifting too far off topic, sorry.
I’ll better inform myself about which insulating coatings are possible; if the rafters are exposed anyway, it might make sense to do that right away.
A
AallRounder17 Sep 2013 14:22Hello,
That probably saved the wooden structure! Otherwise, with the Styrofoam cladding, it might have been much worse.
So now it’s time to grit your teeth again; maybe this winter won’t be too harsh. Next spring, we’ll tackle all this properly!
Whether it’s wise to apply an insulating coating to untreated and well-preserved wood, I wouldn’t want to decide. I only repaired my roof frame, spliced and replaced a few beams, without painting anywhere. But I also maintain a cold roof and, fortunately, don’t have to insulate between the rafters. Instead, I insulated the floor ceilings with clay and allow living moisture to escape upwards.
jfhde schrieb:
... the mortar is more sandy than solid and is barely present in the lower rows, allowing air to flow through the bricks.
That probably saved the wooden structure! Otherwise, with the Styrofoam cladding, it might have been much worse.
So now it’s time to grit your teeth again; maybe this winter won’t be too harsh. Next spring, we’ll tackle all this properly!
Whether it’s wise to apply an insulating coating to untreated and well-preserved wood, I wouldn’t want to decide. I only repaired my roof frame, spliced and replaced a few beams, without painting anywhere. But I also maintain a cold roof and, fortunately, don’t have to insulate between the rafters. Instead, I insulated the floor ceilings with clay and allow living moisture to escape upwards.
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