i'm joined by margaret hagen. margaret, behind you is a beautiful water fall, but where's the pond? water feature. so the water comes down, it goes in to a retaining box and gets recirculated. site goes over and over and over again. reporter: now, we see them installing part of the patio here, and what is unique or special about this patio? >> so this is a perveious paving system, people next to water bodies may need something like this because they have to keep their storm water on site. the way it works is that you put in a ground material that's fairly large, then you put in quarter inch stone, and you follow it up with bedding stone. and that happens before you even put a single paver down. and the idea is that it will hold water so that it infiltrates. so anything coming up through a deck or driveway or roof. reporter: i have pavers here, so we can see that there are different sizes. >> right. this paver is a little larger and thicker. the idea is that because there's a little space, not that big a space, a little space between the pavers, about a quarter inch, then you fill it

i' m joined by margaret hagen. over the years, people have installed pavers, but they break down. margaret: after 10 to 15 years, your patio or walkway will have some we growing through it. some of the pavers are going to be uneven. he needed to lift of those and then you need to restore the sand bed that they rest on, and once you have done that, replace your case pavers. ray: installing an edge restraint, why is that important? margaret: if you don' t, your walkway will separate out. you can buy this at a hardware supply store and is them about one foot apart. >> step three involves pressure washing. why do we need to do that? margaret: to get moss all the stones or debris. clean them up a little bit. >> it we are with the step 4 and we have some stand. what we doing with this? margaret: it is to stabilize the joints. you can' t just use any -- >> our final step is ceiling. what we going to do here? margaret: we are going to be using this water-based sealer and this will bring out the color on the brakes and will help to seal the sand in a little bit. ray: we have had some great