The material costs of slate aren't that cheap unless you are buying the box store stuff that has about a 40%-50% cull rate. And the installation costs for slate are a LOT higher than almost any other natural stone, which is in turn higher than any porcelain. Because even gauged slate will vary a lot, slate is a lot of work to get set correctly without a lot of lippage. It's best set in an old fashioned mud bed rather than with conventional thin set, and there simply aren't a lot of people out there that have the skills to do that anymore. Plus, it takes up more thickness for the floor, and you have to account for that from the beginning of the design if you want flush transitions. If this is to be a completely covered 3 or 4 season room, then I'd recommend some type of porcelain, even a faux slate if you like the look, together with underfloor electric heating cables, or hydrionic if you're doing a boiler. Electric won't soley heat the room in winter, but if you are using a woodstove, it will help keep your feet warm. If you do the PEX for the water, it will provide a toasty warm and comfortable environment for the winter months if you also use good quality windows. If you're not up for putting in high dollar windows, then forget heating the space int he winter and have a 3 season rather than 4 season room. You should make sure that your slab is insulated properly from the surrounding soil regardless of if you choose in floor heating or not if you want to use this in the colder months.

Yo Ken, if your still around your up on this one. Far as Composites go I am with the Larry/whoever We are for the most part. Composites are really no longer using recycled material because there is just not enough of it so most of the raw stuff is virgin,the energy used to make composite is an enviro no no, when its time to remove the project composite is not real big on bio degrade its tricky to burn shreading it would be silly. Bottom line composites are not so enviro freindly. Info like that might suggest its not all that good to clean it either, with anything. I dont agree>> composites will out last Ipe, left to go silver/gray Ipe is as close to no maintance as a person can get. With the softer composites like Choice/MoistureShield even trex= tjunk I have found a coat or two of TWP 116 seals up the decking,locks in the color and keeps mold,mildew,stains from causing major problems. Of course not needing to do this is the reason the Wallet goes for composite in the first place. I my own self dont like composites at all for the reasons stated in several posts here and on other sites. Welcome aboard Larry!!! Sorry I dident understand your intent at the begining . John

Hello RumRunner, You are wise to consider moisture before constructing your deck. Standard decking and T&G will react the same to moisture. T&G is a beautiful option in a covered porch. Your slope and ventilation will be fine. Be sure soil under deck is packed smooth without large ruts. Cover with plastic with large rocks on top to secure it. I read this on a BWDepot.com blog, used it several times and have only happy customers. Congratulations on your new deck.

I think all the ideas that I've read in response to your question are great. You have a lot of things to think about. Is it on the main level of your house or on the lower level? Upper level will certainly block light coming into the room(s) it overhangs, Do you live where you will use it all year long, or just in the milder weather? When there's a really heavy downpour or several days of rain, how does the water flow around your house and patio? Will it be just screens, or will you put in windows so you can use it all year long? That will make it heavier and might need more support at the bottom. We bought our house 6 years ago and the screened-in porch, built on top of the bluestone patio, was already here. It is on the lower level of the house so the roof doesn't shade the main living areas. Although I would have loved it on the main level, I have come to the realization that it's better on the garden level. I have a beautiful wisteria plant covering the roof that can be seen from the dining room window. I believe there was a cement patio originally. The previous homeowner, who is a Master Gardner created a beautiful garden in the back yard with 3 terraces and a stone walkway all through it. Up against the house, she covered the original cement patio with bluestone slabs and then continued it out into a nice large patio. The stones inside the porch have cement between them but outside the porch they have dirt. Even though there are weeds in the section with dirt, I'm sure it was designed that way to let the rain water drain away from the base of the porch. Our house sits on sloping property so the rain runs down the side yards and out into the garden. All the gutter downspouts empty into drain pipes that then run underground until they get to the back yard where they drain into the garden too. All this helps to keep the water away from the base of the screen porch. I get a little water seeping in, in one corner where it's attached to the house, if I don't keep the gutters clear and the overflow from 2 stories up, falls directly into that corner. I use the porch from April to October. It faces east and is a wonderful way to start the day, with the morning sun streaming in. Good luck. I'm sure it will be awesome!!