Problem: Wall ties dirty: can cause damp spots to appear on the inside plaster, sometimes with ‘salt’ or black mould. Remedy – use a metal detector to locate the ties on the outside, examine with a borescope and remove a brick or block from the wall and clean the ties.
It depends on how high the dpc is off ground level or how deep the foundation is in the ground, if possable use a trench block in the ground or if using concrete blocks use wall ties every two course (450 high & 900 long) then fill cavity with a lean mix of concrete to a level of 150mm below dpc.
Beside this, Why am I getting damp on my walls?
The most common cause of both rising and penetrating damp is inadequate ground and surface drainage. … This moisture can make your walls feel wet as it is prone to causing damp patches on walls after heavy rain. You may even see water flowing onto the floor from the edge of the wall.
Likewise, How do I know if my wall ties need replacing?
Horizontal Cracks in Brick Mortar Cracks along the masonry and brick mortar are tell-tale signs that wall ties have deteriorated and started to rust. As the tie rusts, the volume of rust expands inside the mortar where it sits. Over time, widespread buildup of rust can actually crack the mortar between bricks.
Also, How do you inspect cavity wall ties?
locate a number in each elevation using a metal detector, drill holes nearby and look at the tie within the cavity with an endoscope. Often we can see the heavy corrosion and de-lamination. If there is any doubt as to the condition of the wall ties, we expose the outer end by taking out the surrounding mortar.
How often do wall ties need replacing?
How long do they last? Prior to 1978, wall ties were usually manufactured from galvanised mild steel. These ties were expected to last the lifetime of the building, but it has since been recognised that these wall ties can corrode after only 15-20 years.
24 Related Question Answers Found
Should you fill the cavity below DPC?
The cavity below DPC should be filled with concrete up to a level 225mm below DPC – otherwise the weight of the backfill either side of the wall can cause the blockwork to collapse inwards on the cavity below ground (unless the foundations are tench fill in which case there will be very little cavity wall below DPC in …
Should I fill my cavity wall?
If your home was built after the 1920s, chances are it’s got cavity walls. And unless it was built within the last 20 years, those cavities are probably empty. If so, filling them with wall insulation could be a very cost-effective way to retain heat in your home and save on your energy bills.
What blocks below DPC?
Aggregate concrete blocks have been used below damp proof course for many years where they have proved to be durable, efficient and highly economical. Aggregate concrete blocks permit fast on-site working since the standard dimension of a block is equivalent to six bricks.
What are cavity wall ties used for?
These ties are used to connect multiple wythes of masonry, often of different materials; anchor masonry veneer to backing systems other than masonry; and connect composite masonry walls.
What are the disadvantages of cavity wall insulation?
General Cavity Insulation Disadvantages: If moisture gets into your cavity insulation, its ability to keep your home warm will diminish. Cavity fill insulation means you’ll no longer have a void in the cavity to prevent moisture getting across to the inner leaf of the wall. If poorly fitted it won’t be as effective.
Do you put mortar under DPC?
You don’t need mortar under a DPM or DPC.
Can cavity wall insulation cause health problems?
Although it has no health effects when fully sealed within the cavity, if it escapes through gaps it can be a bit of a nightmare. Although blown fibreglass insulation isn’t classed as hazardous, it is an irritant – if it escapes, it can really itch your eyes and skin.
Can you use Thermalite blocks below DPC?
The inherent frost resistance of Thermalite blocks means that all products within the range are suited for use below dpc level. The mortar properties should be appropriate to the degree of frost resistance required.
Are Thermalite blocks waterproof?
Do Thermalite blocks absorb water? … The problem is with thermalite, it’s an airated block and soaks up water and frost will blow them, rendering is very much like plaster but sand and cement is used, to lay a coat over the block work this will normally protect it from the weather.
Do you need a cavity tray at DPC level?
There isnt normally a cavity tray at dpc level, unless in instances where the likes of a Radon Barrier is required, which should overlap inner wall, cavity and outer wall. You would then need a cavity tray above with weep holes.
Does cavity wall insulation go below DPC?
(b) wall insulation Where cavity insulation batts or slabs start below dpc level, the vertical and horizontal spacing of wall ties should be compatible with the spacing to be used above dpc level.
Do I need wall ties?
Hidden from view after construction, wall ties play a vital role in ensuring the stability of a building. Insufficient or poorly installed wall ties can lead to severe structural issues, including damp penetration, masonry cracks or even the collapse of the outer masonry leaf.
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