The Process of Fitting External Insulation in Practice
Since people are always curious about how exactly External Insulation works in practice, we have put together this web page showing actual projects in the Dublin area. Naturally one of the first steps is the delivery of the required external insulation materials
At the level of the damp proof coursing inside the wall we start by fitting a starter board. This will be the level starting line for building up the insulation as well as a drainage adjunct to the DPC.
As the project progresses we will install Extruded Polystyrene insulation below the starter track and your choice of insulation above the starter track. Extruded Polystyrene has excellent hydrophobic properties in standing water and so is idea for ground level areas.
Traditional concrete window sills are simply thermal bridges permitting heat to flow from the home. We normally remove and replace them. By cutting the window sills back so they are flush with the existing wall we can bring the new insulation right up to the window ledge.
We attach the specified insulation (Rockwool, Polyisocyanurate or Graphite Enhanced Expanded Polystyrene) to the clean and dry wall using a chemical adhesive initially. Careful monitoring and adjustment to the amounts of adhesive permits us to correct any alignments flaws in the old wall.
If there is a very heavy and uneven finish it can be smoothed out before the project starts
Once the insulation is attached to the walls the house will start to warm up as the block work absorbs and retains heat. During the winter this protects the interior from cold and in summer from excessive heat. It saves money on maintenance costs and increases the life of the home, helping to protect from wear and damage.
This is the key to external insulation where the entire fabric of the house becomes a vast thermal fly wheel. Storing energy and gradually releasing it as it keep the temperature of the house steady. This means that the house is no longer heating up and cooling down several times a day. This reduces the bills and the strain on the fabric of the building. Naturally this reduces your carbon footprint as you reduce the burden on the planet.
Any pipes attached to the old facade are lengthened so they can be reattached to the new facade. The point where the pipes pass through the insulation is filled with expanding foam or similar.
Cables can be brought forward to the new facade or buried depending on their profile.
Note1: For safety and security reasons: ESB Networks require that overhead service cables must not be covered or concealed by plaster or any other type of rendering. See here for further information.
Note 2: Care must be taken to ensure that PVC cables do not come in direct contact with expanded polystyrene as outlined in the National Rules of the Electro-Technical Council of Ireland
In this way the entire external surface of the building is covered with insulation. Because it is external insulation there is no doubt about workmanship. Each step is visible and can be recorded for posterity. This sets external insulation apart from other systems where shoddy workmanship can be hidden behind walls.
To ensure that the insulation is tightly attached to your external walls we also use a mechanical anchor. This is basically an insulated pin which lodges in a specially constructed anchor fitting. These fittings are designed to exceed the European standard: Determination of point thermal transmittance of plastic anchors for the anchorage of external thermal insulation composite systems (ETICS). Using both a chemical and mechanical system to attach the insulation to the wall helps protect the householder against and problems with poor workmanship either on site or in the manufacturing facilities.
The exact distribution of mechanical anchors depends of the projected wind loading. Therefore special care needs to be taken on tall buildings and around corners. Quite high negative pressures can be generated in the lee of obstructions.
The same system of chemical adhesive and mechanical anchors is also used to secure the Extruded Polystyrene insulation to the plinth. This is the area closest to the ground and below the Damp Proof Coursing, usually about a foot or 300 mm in height.
Once the insulation has been fully secured we will start with the first layer of cementicous render. Typically we will use about 5 tonnes of renders and adhesives on the average home to build up the final finish.
These layers contain a glass fibre mesh, covered with a plastic coating. Overtime the alkaline environment in the render will corrode the plastic leaving the fibrous glass to strengthen the render. This is especially crucial around sharp corners such as window or door openings. At these corners we use additional sections of fibre mesh for strength.
These under coats of cementious renders need to dry out fully before attempting to complete the External Insulation project. At this point we can add any architectural features requested.
To finish off we normally fit pressed metal window sills. Powder coated aluminium is very popular and gives a huge range of colours to the householder. Alternatively there are also concrete over-sills and architectural polystyrene sills.
The final finish can vary between a very plain sand and cement render to a heavy wet dash or a sparkling dry dash. Plus we can now offer an insulated brick finish which gives a very stylish finish to any home.
Once we are finished you get a sparkling home, which you don’t need to paint or worry about for many years. During which time you will be enjoying much reduced heating bills and doing your bit to help save the planet.