How we work
Ten steps, the same every time
Applying the sealant is the last and the quickest part of the job. Everything that happens before it decides whether the joint lasts two years or ten. That is why we always do it in the same order.
Since 1959
Experience and craftsmanship from Utrecht
Clear communication
Short lines, clear agreements
100% satisfaction
We only leave once you are satisfied
Lasting quality
Top-quality materials for a long-lasting result
The process
From inspection to handover
Inspection
We look at what is there and what condition it is in. Has the joint let go along the flank, or is there a tear down the middle? Those are two different problems with two different causes.
Advice
Sometimes replacing it is not necessary. Then we say so. Sometimes the problem is not the sealant but the substrate, and then new sealant is pointless until that has been sorted out.
Assessing the substrate
Will it hold? Is it dry? Is the joint wide enough? Elastic sealant needs at least 8 millimetres of width. We do not seal anything narrower, because then it tears at the first movement.
Removing the old sealant
Completely, not over the top. New sealant does not bond to old sealant. In buildings from before 1994 we first check whether there could be asbestos in it. If so we cut nothing out and report it.
Cleaning and degreasing
Dust, soap residue, silicone oil and grease are the most common cause of sealant letting go. This is dull work, and that is exactly why it often gets skipped.
Fitting backing rod
Closed-cell PE profile outside and anywhere water gets to it, open-cell PU only indoors and dry. That way the sealant bonds on two sides instead of three. If it also bonds to the bottom, the middle cannot stretch and the joint tears.
Primer where needed
Not everywhere, but where the manufacturer specifies it or where the substrate is porous. Skipping a primer saves ten minutes and costs you the whole joint.
Applying the sealant
With the type of sealant that suits the application, at the right thickness. The depth is the width divided by three, plus six millimetres. The middle thinner than the flanks, otherwise there is no give in it.
Tooling and finishing
Pulled off tight in one movement. This is where you see straight away whether someone knows the trade or not.
Final check and handover
We go over it, clear up and hand over. On commercial jobs you get a video report. On jobs for homeowners, a short set of instructions: how long not to use it, and what to keep away from it when cleaning.
Why step 6 cannot be left out
Two cross-sections side by side of the same joint recess. On the left, with a tick: the sealant is bonded to the two flanks and there is backing rod underneath, so the bottom stays free. On the right, with a cross: the sealant fills the whole recess and is bonded to the bottom as well; a tear runs down the middle of the joint.
- Right. With backing rod the sealant bonds to the two flanks only. The middle can stretch when the building element moves.
- Wrong. Without backing rod the sealant bonds to the bottom as well. At the first movement the middle has nowhere to go and the joint tears open.
Afterwards
Curing and maintenance
Curing takes longer than you think
Sealant cures at roughly two to three millimetres a day, at twenty degrees and normal humidity. So a sanitary joint six millimetres deep is only properly hard after two days. Showering earlier means water in a joint that has not closed yet.
No chlorine
Chlorine-based and abrasive cleaners wash the fungicide out of the sealant and leave the edge porous. After that mould comes back faster than it did before. A mild cleaner and a dry cloth do more than an aggressive spray.
Inspect in winter
External joints are best looked at in the cold season. The building elements have contracted then and the joint is at its widest. That is how you spot loss of adhesion that looks fine in summer.
Our advice for external work: a first check within a year of handover, and every two years after that. That is what the trade works to for facade elements as well. You get a 2-year guarantee on the work carried out; maintenance is what gives the joint its extra years after that.
