underlayment question

[rleach]

About a year ago, i installed some laminate in a laundry and foyer. I used 2mm underlayment. Now we are going to run the laminate in the whole house i have found a deal on some 3mm underlayment. Will it be noticable where the 2 and 3 come together?

Thanks Rick

 

[highup]

That's about 1/64 of an inch. I think being just a doorway you could slide some shim material under the doorway. A thickness of a couple of recipe cards or poster board material? Put a piece of 2mm and 3mm along side each other and see what material works with it. You could add another 3 to 6 inches of 2mm outside the doorway and shim it more gradually instead of sliding shims under the previous edge.
Worst case would be a T-molding.

 

[rleach]

This isn't in a doorway, right now it's going from laminate to carpet. I'm tearing up carpet and doing all laminate

 

[highup]

Here's a diagram if you can figure it out.
The brown is your old floor surface. Playing around with material for shims, lets say it takes 3 layers of shim material. Thin poster board might work. You'd have to experiment. Start the first shim next to where the old 2mm underlayment ended...... go out 4 inches and add a second layer of shim....... add a third layer of shim. ......whatever it takes to come up even.
Now drop in some 2mm to connect the old underlayment to the 3mm.
The lower part of the sketch is just a close up view of the upper part with more descriptions.
You might get away without any shimming, but I've never combined 2mm and 3mm, so personally, I'd try to give the 2mm some gradual lift to meet the new thickness.
You didn't mention if this is over concrete or wood.

 

[highup]

There is also a craft paper/vapor barrier material that might work as shim material. A brand name version is called Aquabar-B
http://www.homedepot.com/p/Fortifiber-500-sq-ft-Aquabar-B-Tile-Underlayment-Roll-70-195/202592567
It's a lot thinner than poster board and might take 3 or 4 or 5 layers and you could shim it out over maybe a 2 foot distance. Duct tape has some thickness too..... be creative.
It all depends on how much money you are saving on the 3mm material. There is a lot of difference in sound quality in a good underlayment and a cheap one. Cheap ones sound clipity-clop like horsies in an old western move when you walk on them. Good underlayments can deaden the sound a LOT. It's not padding, it's for sound deadening.
Got a photo of the area

 

[Nick]

I use 30 lb felt to 15 lb. If i need something thicker i start with shingles .

 

[Ernesto]

Well if its not the same exact laminate and locking mechanism your going to have to use a T-mold anyways.

Otherwise do what nick says.

 

[rleach]

Thanks for the tip. It is being installed on wood. I was lucky to find the same laminate so all good there. I found the underlayment at houzz 500 feet for 67 bucks. The big box stores here sell it for 30 bucks per 100 feet.

 

[highup]

That's a good savings, but it's going to be a lot noisier to walk on than a more expensive type. The higher priced ones deaden the sound of foot traffic considerably better. That's why they cost more.
Be sure that the floors are properly prepped, as in flat. Fill any low spots or sand any high spots to the manufacturers specs or you will regret it.
If the floor is not absolutely flat, the planks will flex slightly as you walk on the floor. That, over time can cause the joints to weaken and planks to move apart. The manufacturer will not warrantee that issue. Leave the proper gap around the perimeter too and especially at the door casings.... make sure the floor isn't locked in or binding at any point. It must have expansion.