Home Energy survey for Hollow Block Home

[spondulix]

Hello AAM,

I have a semi d cavity/hollow block home in suburbia, constructed around 1993. Lower part of the front elevation, up to first floor, is clay brick with a void behind it. The rest is all cavity block. Sort of a weird hybrid I guess.

We're planning a bunch of work on the house. As part of the new regs we're supposed to upgrade to a B2.

Right now we have:

• Dry-lined cavity block walls
• Ancient single glazed windows
• Hole in the wall vents
• Poor attic insulation
• And probably no floor insulation

So we're a mess. Cold and draughty in winter with fat heating bills too.

The upside is that we're south facing so we get plenty of sun and well ventilated because we're very draughty.

I'm not interested in slapping on half-measures of varying quality in the hope that things improve. I want to ensure whatever we pay for works holistically, makes financial sense and results in a genuinely improved home, not e.g. a mouldy one.

I'd like to pay somebody reliable and unconflicted for independent advice on what set of upgrades would be simple, cost-effective and would not result in creating more problems. If they could survey the property that'd be great. I've chatted to a bunch of architects about it, but none of them are specialists on this topic and I've received differing recommendations.

We can't name names here but if anyone wants to PM a reference to me that's fine (edit: don't PM me references plz, it's not allowed). Otherwise I'd just like to know the title of the person I need to contact! Home Energy Consultant? Home Energy Surveyor?

If any AAM folks have advice on it I'm all ears.

Thanks!

 

[RedOnion]

We can't name names here but if anyone wants to PM a reference to me that's fine.

No, the rules are the other way around. You can name people on the forum unless you're a new poster, but not advise by PM.

Unfortunately I've nobody to recommend, but I like the way you're approaching this. I purchased a house with external insulation, which was a poor choice for the way the house is constructed, and I'm going to have to revisit insulation and ventilation when I get around to it. The previous owners took the advice of a salesperson.

Your construction type was fairly typical for 30 or 40 years. I previously renovated a 1950's build with similar construction. You'll probably find that the cavity behind the red brick is minimal, and not enough to insulate effectively. I ended up internally insulating selected walls in that house as a cost effective way, but it was definitely what you've described as a half measure!

 

[SPC100]

https://twitter.com/building_life_

Joeseph Little. I've a lot of respect for this guy after reading some of his earlier articles on insulation and mould risks (think it was more than a decade ago).

Looks like he might be lecturer in architecture now.

I don't know if he would be interested. But he was at least very on the ball on some of the issues you mentioned.

 

[spondulix]

Your construction type was fairly typical for 30 or 40 years. I previously renovated a 1950's build with similar construction. You'll probably find that the cavity behind the red brick is minimal, and not enough to insulate effectively. I ended up internally insulating selected walls in that house as a cost effective way, but it was definitely what you've described as a half measure!

Yeah you're right, I don't think the cavity is worth insulating here, not sure it could be pumped or anything.

I'd be happy to internally insulate if somebody experienced and independent would tell me it's the right thing to do! I've googled for Home Energy Audit and found a few names so I'll take a look at those.

Kind of amazed folks are pouring thousands of euros into this lark, experimentally "upgrading" their dwellings without a clue about the outcome.

Joeseph Little. I've a lot of respect for this guy after reading some of his earlier articles on insulation and mould risks (think it was more than a decade ago).

Yeah I've read his articles on insulating hollow block houses. You'd think there'd be a standard recommended approach for this type of build now, given Dublin is littered with them and they're supposed to be upgraded to B2.

 

[SPC100]

I'd go for external before internal.

 

[SPC100]

I purchased a house with external insulation, which was a poor choice for the way the house is constructed, and I'm going to have to revisit insulation and ventilation when I get around to it. The previous owners took the advice of a salesperson.

Would you mind explaining why it was a poor choice?

 

[RedOnion]

Would you mind explaining why it was a poor choice?

Just not the right choice for the house. The house has a cavity wall.

To explain the extent to which this was a salesperson recommendation - there are still some original single glazed windows to replace!

 

[spondulix]

Would you mind explaining why it was a poor choice?

To further elaborate on what @RedOnion said, a cavity wall is different from a cavity block wall.

Cavity walls are really two walls with a void, or cavity between them. The void should be pumped with insulation or have boards put in there.

Cavity block walls (AKA hollow block walls) should not be pumped as there is cold bridging within the blocks. SEAI will not give a grant for pumping these walls. The general advice is to externally insulate these. I believe you can have success internally insulating also but you need to be very careful not to mess it up. Cavity blocks look like this:



Just emphasizing this so folks are not confused, because it sure can be confusing. The above should not be taken as gospel either, it probably depends on your specific situation. Get a pro to look at it.

 

[paper-folder]

I'd like to pay somebody reliable and unconflicted for independent advice on what set of upgrades would be simple, cost-effective and would not result in creating more problems. If they could survey the property that'd be great. I've chatted to a bunch of architects about it, but none of them are specialists on this topic and I've received differing recommendations.

Spondulix,
Have you considered getting a BER assessor to survey your house? The advice you are looking for is exactly what they are supposed to be experts at. I don't have someone that I can recommend, and I know that they can vary in competence, but a good BER report will highlight the areas where it is worth investing and which will be the most cost effective.

We in similar position about 10 years ago and Iike you realised that a holistic approach was needed. We got additional insulation in the attic, and replaced all windows with triple glazing. We got external insulation on all walls with the exception of the front. Here we retained the original finish to match our neighbours. There was a reasonable gap behind the half brick facade, so we go this pumped with insulation, and the upstairs rooms at the front got internal insulation on their external walls. We found we cut our fuel bills by about 50%, but more importantly, comfort levels within the house improved immensely. 10 years on, we are still delighted with the job. I'm sure that techniques and materials have improved even more, so go for it I'd say!

 

[Leo]

This is a rather good guide of the various construction types typically seen across Ireland with a list of recommended actions in priority to improve energy efficiency. It's from 2014, so the estimated costings of some works are likely to have changed, but it'll guide you in the right direction at least.

 

[TheBig40]

Hello AAM,

I have a semi d cavity/hollow block home in suburbia, constructed around 1993. Lower part of the front elevation, up to first floor, is clay brick with a void behind it. The rest is all cavity block. Sort of a weird hybrid I guess.

We're planning a bunch of work on the house. As part of the new regs we're supposed to upgrade to a B2.

Right now we have:

• Dry-lined cavity block walls
• Ancient single glazed windows
• Hole in the wall vents
• Poor attic insulation
• And probably no floor insulation

So we're a mess. Cold and draughty in winter with fat heating bills too.

The upside is that we're south facing so we get plenty of sun and well ventilated because we're very draughty.

I'm not interested in slapping on half-measures of varying quality in the hope that things improve. I want to ensure whatever we pay for works holistically, makes financial sense and results in a genuinely improved home, not e.g. a mouldy one.

I'd like to pay somebody reliable and unconflicted for independent advice on what set of upgrades would be simple, cost-effective and would not result in creating more problems. If they could survey the property that'd be great. I've chatted to a bunch of architects about it, but none of them are specialists on this topic and I've received differing recommendations.

We can't name names here but if anyone wants to PM a reference to me that's fine (edit: don't PM me references plz, it's not allowed). Otherwise I'd just like to know the title of the person I need to contact! Home Energy Consultant? Home Energy Surveyor?

If any AAM folks have advice on it I'm all ears.

Thanks!

How is this going for you? I’m pretty much doing the same exercise around general insulation and am now trying to future proof a bit.

The couple of companies I’ve contacted start off seeming “independent” but on two occasions have told be about contractors that could do the work, while I don’t mind a recommendation I’m had hoped for “this is what you should do, this is a spec to look for and when you have your quotes we can review them for you” - no issue paying for good advice but everyone so far has had an angle.

 

[spondulix]

Spondulix,
Have you considered getting a BER assessor to survey your house? The advice you are looking for is exactly what they are supposed to be experts at. I don't have someone that I can recommend, and I know that they can vary in competence, but a good BER report will highlight the areas where it is worth investing and which will be the most cost effective.

Yeah I'm doing a BER as a first step. Need to book somebody to do it - if anyone has any recommendations for a good BER assessor feel free to drop one!

How is this going for you? I’m pretty much doing the same exercise around general insulation and am now trying to future proof a bit.

The couple of companies I’ve contacted start off seeming “independent” but on two occasions have told be about contractors that could do the work, while I don’t mind a recommendation I’m had hoped for “this is what you should do, this is a spec to look for and when you have your quotes we can review them for you” - no issue paying for good advice but everyone so far has had an angle.

I haven't embarked on it yet. We'll do the BER first and then make some decisions. It will be quite an expensive process as we're looking to extend at the same time. I have spoken to a couple of architects (5 now!?), trying to get a handle on things. Some of them know more about the energy retrofit game, some less. They've all recommended external insulation as the way to go for our home. I need to square the cost of doing the work vs moving house, which is also an option for us.

From what I can gather external insulation is a tricky job and you need to ensure it's done right. I'd probably hire somebody independent to inspect any work done myself. I've been told it's a good time to replace the windows as ideally they should integrate with the insulation and be moved outward. I've also been told our partition wall should be insulated internally. All this aligns with what I've read. We need new windows anyway, with our single glazing!

Without the deep retrofit scheme we're at a bit at a loss, so hopefully something happens on that front sooner rather than later.

 

[paper-folder]

From what I can gather external insulation is a tricky job and you need to ensure it's done right. I'd probably hire somebody independent to inspect any work done myself. I've been told it's a good time to replace the windows as ideally they should integrate with the insulation and be moved outward. I've also been told our partition wall should be insulated internally.

It seems that there are plenty of ways that all the effort can be negated by bad practices which allow the formation of cold bridges or worse still, which impact on the fabric of the house. Cold bridge prevention includes details like cutting off and replacing concrete window sills and bringing the insulation down to ground level. We got three quotes for the work and didn't go with the cheapest one, we went with the contractor that we were happiest with based on their approach and which fitted in best with our own research.

You definitely need to include replacing the windows; think of the heat like trying to keep water in a barrel, it won't hold over time even if there are small holes! We replaced the windows and went for triple glazing, which also makes a big difference for noise. We didn't move out the windows though. We were advised at the time that this would cost extra due to making good around the internal reveals and re-decoration could be tricky especially if it required matching additional tiles or wall paper with what was already there. There is no great benefit in the space you gain and we didn't notice any particular loss of light due to the deeper external reveal.

We didn't internally insulate the party wall. The driving force for heat transfer is the temperature difference between two surfaces so unless your neighbours have no heating at all, I suspect that this aspect of the job if carried out would have the longest pay-back time. It would be very disruptive for you during installation. Redecoration of whole rooms is likely to be required when internal insulation is being retrofitted to just one wall.

 

[spondulix]

We didn't internally insulate the party wall. The driving force for heat transfer is the temperature difference between two surfaces so unless your neighbours have no heating at all, I suspect that this aspect of the job if carried out would have the longest pay-back time. It would be very disruptive for you during installation. Redecoration of whole rooms is likely to be required when internal insulation is being retrofitted to just one wall.

Yeah full insulation of partition wall is certainly very disruptive. The reason we plan to do it is due to the terrible job that is already there. We have bad sound insulation problems and probably air gaps in the blockwork between ourselves and the neighbour. One architect told me it would help with both thermal and sound insulation to skim the wall and reinsulate, which makes sense I guess. Adds another 10k or so to the bill of course.