How to stop my dog chewing?

I'm hoping someone can give me some advice how to stop my dog from chewing hes a 8 month old alsatian (and yes i do understand hes still a puppy) but anything i seem to do doesn't stop him from chewing. He chewed alot of the skirting in the kitchen aswell as the rug & he even started on the cupboard doors & pretty much everything else, we have a wooden lean to on the side of the house & because his chewing got so bad if we go out during the day we leave him in there because he was destroying the kitchen & he has chewed all over in there too & also when hes in the garden he has chewed the bench & some of the fencing & he has also had a go at the side of the shed. He has got lots of toys but just chews them too we've even bought the expensive really tough rubber ones & he destroyed them aswell, we have a fairly big garden so he has plenty of room to run about so i don't think hes chewing down to boredom & he has daily walks so we don't no what we can do any tips or advice is much appreciated thanks in advance =) PS I've been to pet shop & bought all the sprays & other stuff they tell you will work to stop chewing & believe me it doesn't work on our dog.They are the toys iv had for him & he just chews them (even worse if i put treats in it) & as for a tennis ball that will last all of 5 mins he peels all fur off it then chews the ball to pieces, & i don't work so hes only ever on his own if i go to shop or take my son to school ETC so it isn't for long periods of time. He gets plenty of attention my son can be in the garden with friends & they are all running round playing & shadow (my dog) is sat chewing the bench rather than joining in with them :-S so kind of at a loose end tbh.

Its like a hamster get your dog a tennis ball and some sticks and something squishy and play with him a little more maybe get him those like yellow snowman things that say kowang or something and have a tail I know my old English sheep dog loves them good luck

Well, some of the reasons can be the following :Through loneliness or boredom.Separation anxiety, this form of chewing often occurs if you work long hours away from home.When they are teething (this can be a very trying time for owners).Through fear or a phobia.Seeking attention.Through anticipation, some dogs chew just before their owner is due to arrive home.Here can be some fixes :Provide your dog with a few tasty chew toys. Make it perfectly clear to your dog that if he/she needs to chew, it must be on the chew toys. It's a good idea to toss a dog toy stuffed with some tasty treats to your dog as you leave for work each morning.Provide your dog with lots of exercise, both physical and mental when you are at home (games, obedience training, tricks...)

1. Don't allow a puppy full access to a house...pen him up where he can't get into things.2. Give him lots of rawhide bones and puppy safe toys to chew until he stops teething.3. CORRECT the dog when he goes after something he is not supposed to chew on, tell him now, and move him away from the item and tell him no again. If he won't listen, get his attention with a rolled up news paper (don't hit the dog, just hit the ground and make a loud noise). You have to actually TRAIN a dog what is right and what is wrong to do in your house.

I have a pitbull puppy and he chewed up EVERYTHING including toys we bought him an Extreme Kong and not only does he love it but it is literally the ONLY thing he hasn't been able to chew up!! They also make stuff for you to put inside like a paste type substance and it will keep your dog busy for a while!!My puppy loves it and like I said the ONLY thing he hasn't been able to chew it up it doesn't even have teeth marks and he has had it for 3 months now!!