I have a litter of 4, medium sized pastoral breed, they are almost 6 weeks old. At the moment they are in my lounge with a puppy pen cordening off a corner of the room so that they have ample space to trash!
They are now at the age of destruction (nicknamed the gruesome twosome and the terrible twins) and have ripped through two lots of double layered tarpaulin that protects my wooden floor under the pen, so I feel they need to be moved to the kitchen- which isnt huge but has tiled floors.

My concern is that the puppy pen will have to be made smaller, so will meaure approx 44x44" which isnt huge I know, they obviously spend alot of time out of the pen, and mum doesnt go in with them at all now (her choice). Is this adequate? or shall i just persevere with them in the lounge in their pen which measures 44x68" ?

Why don't you buy a cheap lino offcut & put it under their pen?  I doubt they would be able to destroy it & if you make it a bit bigger than the pen  put it underneath it - they won't be able to get at the edges.  Quite easy to clean & the better quality is non-slip.

my pups, Medium sized Gundog breed have a 5 ft x 10 ft play pen. I have reared 13 in this size pen and they have had plenty of play room.

Mine sleep in their pen and stay in their whilst eating but hte rest of the time they're just out in the living room or kitchen with me; I agree about the lino cut then, might save your floors!

I moved them into the kitchen/utility now, attached the pen onto a large crate (door open all the time) so they have plenty of room.

They have to have designated times out, they de-sole shoes, pull wires out, lift the carpet..and chew lumps of coal on my NEW beige carpet (that happened earlier!).

Dog owner = beige carpet = NO!! lol

Tell me about it! LOL!

At this age my pups have a 6 foot long by s feet one side and 3 foot the other under a breakfast bar in the kitchen.

This is usually used at night and when they are resting, the rest of the time they have  12 x 10 foot dog run attached to an outdoor kennel outside the kitchen window so they have space and shelter.

A pig board across the open doorway of the dog run allows the adults to come and go and interact with pups (except when they are having meals).

I shuttle them between the indoor and outdoor facilities based on cleaning out feeding and what they are doing (resting or rough housing).

I have never managed to happily contain a litter of my breed (medium Spitz) wholly within their inside accommodations beyond 5 weeks, even with a litter of only 3..

Puppies need space to develop muscles and need fresh air.

Don't get me wrong- they are not shut in their all day, they play in the garden at least 5 times a day for half an hour each time and on top of that are probably out of their pen for 6+ hours a day, but I have to put them away in the pen for my sanity!

Fortunately I have tiles in the kichen, but I know your pain!!!!

While pups are in the livingroom I have used Large Lino offcut under puppy pen, with paper on top you won't get wet travel over the edges, if there is a decent margin.