This lecture looks at the construction sequence for a simplified cavity wall construction. This example is a partial fill cavity but the principles apply to other types of wall as well.
Are cavity walls only on the exterior walls of houses? Or the interior as well, for example a brick wall separating two bedrooms? How thick are interior walls? And if you have a terraced house, where your neighbours wall meets is there a cavity there?
Hi Daniel, thanks for the question. If it is a detached house then yes, the cavity walls are usually only on the outside walls. The main function of them is to stop water entering. Where there are brick walls inside, say between rooms, the thickness is probably around 150mm (one brick plus two coats of plaster). For walls between houses it very much depends on how old the house is. Up to around 1950 it was usual to have a solid wall between houses, for houses built after that it will probably have a cavity as they were introduced to combat sound passing between dwellings. Hope this helps.
@@Ramstam ah I see so to sum this up. Cavities are only on the exterior walls of the house and interior walls are solid walls. This is usually the case when the houses were built 1930s+?? I just assumed the walls that are up against houses are solid. Also is there an easy way to tell if a wall is solid or has a cavity??
Hi Daniel, sorry for the late reply. An easy way to tell if a wall is a cavity wall is to look for the weep vents between the bricks. You can usually see these lower down the wall at DPC level and also above lintols. You are right, cavity walls are usually used on the outside as they help protect the building from rain. Cheers
Hi, Thanks for the question. I think the timestamp in your question might be wrong as the video is only 11:08 long. I'm guessing that its the picture at 9:08? If so the white things sticking through the scratch coat are weep vents (sometimes called perpend vents). they allow air into the cavity and can also let water out. You can see them explained in the next video of this series 2-14. Hope this helps
In the UK there are a couple of criteria for developing the thickness of walls. For external walls (which tend to be loadbearing) the first criteria would be that it needs to handle the loads of the building above. This is dependant on the size and height of the building, the ground that it sits on and what material it is made of. The second criteria is that it would probably be the place where insulation is placed so the thickness might be governed by the required depth of insulation. In Scotland we tend to design with timber frames and place the insulation between the studs; to get enough insulation in this location the frame would probably exceed 175mm. If you added a brick outer leaf and some internal drywall it might mean an external wall of around 350mm or more. For internal walls the most significant issue is probably sound. A n internal wall (partition) should be able to reduce air-borne sound and impact sound so its likely that they will be either made of stud framing with plasterboard (drywall) or made from solid concrete block. Either will probably result in a wall of between 125mm and 150mm. Hope that helps,
Hi, thanks for the question. The radon barrier is similar to a DPM and it should protect the whole house. For interior walls that have foundations under them it would need to be lapped up and over (have a look at the video for interior load bearing partitions). Hope that helps.
In Scotland we tend to talk about solid walls rather than monolithic, but I know what you mean. If you were asking which is best then I'd have to say it very much depends on the situation; where it is, what the desired fabric efficiency is and what materials were available.
Very well described, thank you.
this is great, thank you
Glad you like it!
Some man👍🏽
Are cavity walls only on the exterior walls of houses? Or the interior as well, for example a brick wall separating two bedrooms? How thick are interior walls? And if you have a terraced house, where your neighbours wall meets is there a cavity there?
Hi Daniel, thanks for the question. If it is a detached house then yes, the cavity walls are usually only on the outside walls. The main function of them is to stop water entering.
Where there are brick walls inside, say between rooms, the thickness is probably around 150mm (one brick plus two coats of plaster).
For walls between houses it very much depends on how old the house is. Up to around 1950 it was usual to have a solid wall between houses, for houses built after that it will probably have a cavity as they were introduced to combat sound passing between dwellings. Hope this helps.
@@Ramstam ah I see so to sum this up. Cavities are only on the exterior walls of the house and interior walls are solid walls. This is usually the case when the houses were built 1930s+?? I just assumed the walls that are up against houses are solid. Also is there an easy way to tell if a wall is solid or has a cavity??
Hi Daniel, sorry for the late reply. An easy way to tell if a wall is a cavity wall is to look for the weep vents between the bricks. You can usually see these lower down the wall at DPC level and also above lintols. You are right, cavity walls are usually used on the outside as they help protect the building from rain. Cheers
at 11.08 on the video. the right wall that has a scratch coat ,what are the white things protruding out near the bottom ,cheers
Hi, Thanks for the question. I think the timestamp in your question might be wrong as the video is only 11:08 long. I'm guessing that its the picture at 9:08? If so the white things sticking through the scratch coat are weep vents (sometimes called perpend vents). they allow air into the cavity and can also let water out. You can see them explained in the next video of this series 2-14. Hope this helps
Just wondering if there are the thickness requirements for both inner walls and outer walls??
In the UK there are a couple of criteria for developing the thickness of walls. For external walls (which tend to be loadbearing) the first criteria would be that it needs to handle the loads of the building above. This is dependant on the size and height of the building, the ground that it sits on and what material it is made of. The second criteria is that it would probably be the place where insulation is placed so the thickness might be governed by the required depth of insulation. In Scotland we tend to design with timber frames and place the insulation between the studs; to get enough insulation in this location the frame would probably exceed 175mm. If you added a brick outer leaf and some internal drywall it might mean an external wall of around 350mm or more.
For internal walls the most significant issue is probably sound. A n internal wall (partition) should be able to reduce air-borne sound and impact sound so its likely that they will be either made of stud framing with plasterboard (drywall) or made from solid concrete block. Either will probably result in a wall of between 125mm and 150mm.
Hope that helps,
does a radon barrier overlap both the internal and external wall,,cheers
Hi, thanks for the question. The radon barrier is similar to a DPM and it should protect the whole house. For interior walls that have foundations under them it would need to be lapped up and over (have a look at the video for interior load bearing partitions). Hope that helps.
@@Ramstam thanks
Good
Thanks
You are most welcome
Cavity wall VS monolithic wall
In Scotland we tend to talk about solid walls rather than monolithic, but I know what you mean. If you were asking which is best then I'd have to say it very much depends on the situation; where it is, what the desired fabric efficiency is and what materials were available.