Does concrete ring beam = cold bridge ?

pajosjunkbox

Hi ,

I'm building a vaulted ceiling living space . It will have 3 steel beams running horizontally across . The engineer has also detailed a concrete ring beam on top of the wall plate with cavity closed with a slate.

Structurally I understand this needed to stop force on walls. My only issue is that this concrete ring beam will not be insulated and therefore will be a cold bridge running around the perimeter of room.

Is there anyway to insulate this or is it a necessary evil ?

Thanks

Metric Tensor

Yes. It's a cold bridge but it is almost certainly needed unless you want to go to the expense of steel portal frames instead. It's impossible to comment on these things for certain without knowing the specifics of the project.

I don't know what stage your house is at but if you built a wider inner leaf your engineer might be able to fit the ring beam on top of that and then run the cavity insulation right up the outside of it. It would make the blockwork more costly of course.

Rabbo

Does the ring beam cross over the cavity? If so, it probably is a thermal bridge. One way of avoiding this is having a 215mm block inner leaf which might give enough width so that the ring beam sits on the inner leaf only and not cross the cavity. This is subject to a 215mm wide ring beam for the loading involved which can only be verified by your engineer

EDIT: oops, just saw metric tensors post

pajosjunkbox

Thanks for the input . Much appreciated. The ring beam is 225 x 325. Intake it the a ring beam to take the weight of the vaulted roof is pretty much the norm.

In reality, if I don't increase the inner leaf to accommodate ring beam and it is a cold bridge, would this create condensation on that part of the wall. Or is it a case that there will be just more heat escaping from that part of the wall.

Dudda

pajosjunkbox wrote: »

Thanks for the input . Much appreciated. The ring beam is 225 x 325. Intake it the a ring beam to take the weight of the vaulted roof is pretty much the norm.

In reality, if I don't increase the inner leaf to accommodate ring beam and it is a cold bridge, would this create condensation on that part of the wall. Or is it a case that there will be just more heat escaping from that part of the wall.

condensation, heat loss and possible mould growth.

Is it 325mm wide? How wide is the cavity? I presume it's currently 100mm inner and outer block? Are you drylining internally? Need more info before advising on how to detail out the problem.

Victor

Another risk would be penetrating damp, but it would be rather low.

As mentioned, consider dry-lining internally or external insulation.

BryanF

yes thermal bridge

Get someone to solve it

If the lads will do it for you here, fare play to them. This is what you pay your Eng for.

Mellor

Dudda wrote: »

condensation, heat loss and possible mould growth.

Is it 325mm wide? How wide is the cavity? I presume it's currently 100mm inner and outer block? Are you drylining internally? Need more info before advising on how to detail out the problem.

Presumably it's 225. If it's not, it should be as it's stronger in that orientation.
There's a couple of solutions that come to mind depending on side conditions and intended architectural style. And obviously where the insulation is located.

As for the risks. It will cause more heat to escape which will also encourage condensation to settle on the beam

pajosjunkbox

I asked my engineer about the cold bridge issue previously and he agreed it would be a cold bridge but that it was necessary to support roof.

His main concern is that the building is structurally sound and I understand his position. If there was a way around it or something I could do to lessen the likelihood of a cold bridge I'd love to hear it if anyone has any ideas.

The width of the wall including cavity shows 325mm but I'm increasing insulation to 150 mm from 125 mm so now wall and cavity will be 350mm. So that's 100mm block, 150mm full fill board, 100mm block.

There is no internal insulated plasterboard.

BryanF

Loads of option on this.

But it's your engineers job to solve this.

If he is taking the attitude that it a though sh1t situation, and he is only responsible for part A (structure) of the building regs. then you need to hire an arch/arch tech to detail this building to meet part L of the building regs.

What your engineer is offering goes against the spirit of the building regulations particularly part L, and as such you as the responsible party needs to sort this out.

Keen to help out a fellow self-builder, but personally as this is my day job, I'll be stopping short of designing your specific detailing problems caused by the guy you hired to do this job.

Bonzo Delaney

Is this not what light weight steel lintels were designed for to solve the problem of cold bridging while maintaining the structural support of a ring beam why can't a steel lintel be used here.

pajosjunkbox

I'll look into that. Thanks Bonzo.

Penn

Bonzo Delaney wrote: »

Is this not what light weight steel lintels were designed for to solve the problem of cold bridging while maintaining the structural support of a ring beam why can't a steel lintel be used here.

Sorry but that is completely incorrect. Lintels are for opes in a wall, designed for vertical loading. A ring beam goes around the perimeter of the wall under the wallplate to provide lateral/horizontal resistance where there is no or minimal triangulation in the roof.

OP without being able to look at drawings etc to properly assess the situation, you likely have two options in this case. You could build the inner leaf as a block on flat 215mm wall with the ring beam on top. Then the insulation in your cavity can come the full way up and prevent cold bridging. Or you could use a steel beam built into the ridge of the vaulted roof. This will reduce roof spread and should negate the need for a ring beam and you can build the walls as per standard. Your engineer should be able to assess both options. However, he does need to take into consideration the issue of thermal bridging as part of his design, otherwise he is not performing his duties and responsibilities correctly. These aren't new details, and he should be familiar with ways to satisfy the structural requirements with minimal thermal bridging issues.

Bonzo Delaney

Penn wrote: »

Sorry but that is completely incorrect. Lintels are for opes in a wall, designed for vertical loading. A ring beam goes around the perimeter of the wall under the wallplate to provide lateral/horizontal resistance where there is no or minimal triangulation in the roof.

OP without being able to look at drawings etc to properly assess the situation, you likely have two options in this case. You could build the inner leaf as a block on flat 215mm wall with the ring beam on top. Then the insulation in your cavity can come the full way up and prevent cold bridging. Or you could use a steel beam built into the ridge of the vaulted roof. This will reduce roof spread and should negate the need for a ring beam and you can build the walls as per standard. Your engineer should be able to assess both options. However, he does need to take into consideration the issue of thermal bridging as part of his design, otherwise he is not performing his duties and responsibilities correctly. These aren't new details, and he should be familiar with ways to satisfy the structural requirements with minimal thermal bridging issues.

Well it can be an option if designed correctly as it's what I have on my house . And performs both duties
But like you said with out drawings it's hard to tell

pajosjunkbox

Thanks Penn. Both block on the flat and steel beam in ridge viable options I think. Would hate to have a cold bridge running the perimeter of the room while trying to minimise heat loss everywhere else.

Room is straightforward rectangle 13 x 6.4 metres. 2.9 to wall plate. Vaulted ceiling that flattens out near the top if that makes sense.

I can post floor plan if thats allowed ?

Aid62

Well said Bryanf . I have serious reservations about engineers on dwellings if they are not qualified to design a building they must excuse themselves from it.

On dwellings structure while very important isn't the be all of building.

Loads of more appropriately qualified people out there.

Civil and structural engineers should stick to civil and structural engineering only!
If your engineer designed a cold bridge he is in breach of the building regs which is not acceptable. You should check his code of ethics too

Aid62

Well said Bryanf . I have serious reservations about engineers on dwellings if they are not qualified to design a building they must excuse themselves from it.

On dwellings structure while very important isn't the be all of building.

Loads of more appropriately qualified people out there.

Civil and structural engineers should stick to civil and structural engineering only!
If your engineer designed a cold bridge he is in breach of the building regs which is not acceptable. You should check his code of ethics too

Mahogany Gaspipe

Christ some of you don't half make a dramatic meal out of simply queries around here!
Its a relatively straight-forward detail not specifying foundations for a nuclear power station in an earthquake zone. 

OP, does the ridge line of the roof run into gabled or hipped end; or perhaps lays onto adjacent roofs?

Mellor

Mahogany Gaspipe wrote: »

Christ some of you don't half make a dramatic meal out of simply queries around here!
Its a relatively straight-forward detail not specifying foundations for a nuclear power station in an earthquake zone. 

OP, does the ridge line of the roof run into gabled or hipped end; or perhaps lays onto adjacent roofs?

What dramatics?
OP ask it it's was a cold bridge. They were told that it was.

Mahogany Gaspipe

Mellor wrote: »

Mahogany Gaspipe wrote: »

Christ some of you don't half make a dramatic meal out of simply queries around here!
Its a relatively straight-forward detail not specifying foundations for a nuclear power station in an earthquake zone. 

OP, does the ridge line of the roof run into gabled or hipped end; or perhaps lays onto adjacent roofs?

What dramatics?
OP ask it it's was a cold bridge. They were told that it was.

Depending on the simply geometry of the roof; the RC beam (and hence the occurrence of that cold bridge) may not be required.

pajosjunkbox

Going with a ridge beam now instead of a concrete ring beam. Hopefully this will keep cold bridging to a minimum. Thanks for all the helpful input.

Mellor

Mahogany Gaspipe wrote: »

Depending on the simply geometry of the roof; the RC beam (and hence the occurrence of that cold bridge) may not be required.

The question was "is a ring beam a cold bridge?", not is a ring beam/cold bridge required.


I'd argue that regardless of how simple or complex the geometry is, a concrete ring beam can always be avoided is the engineer wants to any think other than the minimal work.

tradesman

Surely a steel lintol is also a cold bridge?

pajosjunkbox

Yes the ridge beam is a cold bridge but finished ceiling will be underneath it and will be well insulated so it won't affect the room.

The concrete ring beam would have been a cold bridge in the room. We could of used insulated slabs internally to cover concrete ring beam but I didn't want to do this after researching insulated slabs.